Displaying publications 61 - 80 of 164 in total

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  1. Abu MN, Samat S, Kamarapani N, Nor Hussein F, Wan Ismail WI, Hassan HF
    PMID: 25821506 DOI: 10.1155/2015/985042
    The antidiabetic properties of Tinospora crispa, a local herb that has been used in traditional Malay medicine and rich in antioxidant, were explored based on obesity-linked insulin resistance condition. Male Wistar rats were randomly divided into four groups, namely, the normal control (NC) which received standard rodent diet, the high fat diet (HFD) which received high fat diet only, the high fat diet treated with T. crispa (HFDTC), and the high fat diet treated with orlistat (HFDO). After sixteen weeks of treatment, blood and organs were harvested for analyses. Results showed that T. crispa significantly (p < 0.05) reduced the body weight (41.14 ± 1.40%), adiposity index serum levels (4.910 ± 0.80%), aspartate aminotransferase (AST: 161 ± 4.71 U/L), alanine aminotransferase (ALT: 100.95 ± 3.10 U/L), total cholesterol (TC: 18.55 ± 0.26 mmol/L), triglycerides (TG: 3.70 ± 0.11 mmol/L), blood glucose (8.50 ± 0.30 mmo/L), resistin (0.74 ± 0.20 ng/mL), and leptin (17.428 ± 1.50 ng/mL) hormones in HFDTC group. The insulin (1.65 ± 0.07 pg/mL) and C-peptide (136.48 pmol/L) hormones were slightly decreased but within normal range. The histological results showed unharmed and intact liver tissues in HFDTC group. As a conclusion, T. crispa ameliorates insulin resistance-associated with obesity in Wistar rats fed with high fat diet.
    Matched MeSH terms: Alanine Transaminase
  2. Kadum Yakob H, Manaf Uyub A, Fariza Sulaiman S
    J Ethnopharmacol, 2012 Aug 1;142(3):663-8.
    PMID: 22705121 DOI: 10.1016/j.jep.2012.05.035
    Ludwigia octovalvis (Jacq.) P. H. Raven (Family: Onagraceae), as a traditional Malay herbal medicine,has been used to treat gastrointestinal complaints such as diarrhea and dysentery.
    Matched MeSH terms: Alanine Transaminase/blood
  3. Chua YA, Nurhaslina H, Gan SH
    Methods Find Exp Clin Pharmacol, 2008 Dec;30(10):739-43.
    PMID: 19271022 DOI: 10.1358/mf.2008.30.10.1316830
    Because durian (Durio zibethinus), which is known in Southeast Asia as "the king of fruits", is thought to have special body-warming properties, it should not be consumed with paracetamol due to a risk of toxic effects. The claim of warming properties, however, has not been scientifically proven. This study was conducted to investigate durian's hyperthermic effect and its toxicity when consumed together with paracetamol in rats. Five groups of rats (n=6) were fed with: 1) distilled water (4 ml/250 g), 2) homogenized durian (4 g/250 g), 3) paracetamol solution (2400 mg/kg), 4) durian (4 g/250 g) followed by paracetamol solution (2400 mg/kg), or 5) prazosin solution (15 mg/kg, pregavaged) followed 1 h later by durian (4 g/250 g) and paracetamol solution (2400 mg/kg). Rectal temperature, systolic blood pressure and serum alanine aminotransferase (ALT) levels were taken from each rat at baseline and after the various administrations at 1, 2 and 5 h. Our results showed that the body temperature of rats in the durian-treated group was not significantly elevated when compared to the control. However, there was a significant decrease in body temperature over time in animals from groups 4 and 5. We did not, however, observe a consistent pattern of blood pressure change. Serum chemical analysis for ALT also did not show any significant change in any of the groups. In conclusion, contrary to what some believe, even though durian was found to increase body temperature in some rats, this increment was not significant. Rats receiving the durian-paracetamol combination showed a significant drop in body temperature, which may explain the belief that the two mixtures are toxic. However, the exact mechanism of toxicity is still unknown.
    Matched MeSH terms: Alanine Transaminase/blood
  4. Ooi ET, Ganesananthan S, Anil R, Kwok FY, Sinniah M
    Med J Malaysia, 2008 Dec;63(5):401-5.
    PMID: 19803300
    This is a retrospective study of the gastrointestinal symptoms, signs and laboratory parameters in adult dengue patients admitted to Kuala Lumpur Hospital from 1st December 2004 to 31st December 2004. Clinical and laboratory parameters that may predict the need for intensive care were investigated. Six hundred sixty-six patients with clinical and biochemical features consistent with dengue infection were identified. Patients were stratified into those who required intensive care and those who were managed in non high dependency wards. Serum alanine aminotransaminase (ALT) levels were normal in 22.8% of patients and 5.9% of patients had acute fulminant hepatitis. More patients with dengue haemorrhagic fever (DHF) had elevated ALT levels as compared to patients with classic dengue fever (DF) (p = 0.012). Patients with DF had a statistically significant lower mean ALT level as compared to patients with DHF. Abdominal pain (p = 0.01) and tenderness (p<0.001), gastrointestinal bleed (p<0.001), jaundice (p<0.001), hepatomegaly (p<0.001) and ascites (p<0.001) were predictors of need for intensive care. We conclude that gastrointestinal manifestations are very common in dengue patients. Presence of abdominal pain and tenderness, gastrointestinal bleed, jaundice, hepatomegaly and ascites can be used to triage patients requiring intensive care.
    Matched MeSH terms: Alanine Transaminase/blood
  5. Tan BL, Norhaizan ME, Pandurangan AK, Hazilawati H, Roselina K
    Pak J Pharm Sci, 2016 Jan;29(1):205-12.
    PMID: 26826813
    Brewers' rice is one of abundant agricultural waste products in the rice industry. The present study is designed to investigate the potential of brewers' rice to inhibit the development of aberrant crypt foci (ACF) in colon of azoxymethane (AOM)-treated rats. The effects on the attenuation of hepatic toxicity and kidney function enzymes were also evaluated. Male Sprague-Dawley rats were randomly divided into five groups: (G1) normal; (G2) AOM alone; and (G3), (G4), and (G5), which were AOM fed with 10%, 20%, and 40% (w/w) of brewers' rice, respectively. The rats in group 2-5 were injected intraperitoneally with AOM (15 mg/kg body weight) once weekly for two weeks. After 8 weeks of treatment,the total number of ACF/colon and the number of ACF in the distal and middle colon were significantly reduced in all treatment groups compared to G2 (p<0.05). Brewers' rice decreased the number of ACF with dysplastic morphology in a dose-dependent manner. Alkaline phosphatase (ALP) level in G5 was significantly lower compared to the G2 (p<0.05). In conclusion, this study found the potential value of brewers' rice in reducing the risk of cancer susceptibility in colon.
    Matched MeSH terms: Alanine Transaminase/blood
  6. Wahid SF, Sanusi S, Zawawi MM, Ali RA
    PMID: 11127322
    The impact of dengue on liver function was studied on fifty serologically confirmed dengue cases admitted to Hospital Universiti Kebangsaan Malaysia (HUKM). Twenty-five of these patients had classic dengue fever (DF) and 25 had grade 1 or 2 dengue hemorrhagic fever (DHF). There were more (60%) DHF patients with hepatomegaly compared to DF (40%) but the difference was not statistically significant. Analysis of the liver profile showed that liver dysfunction was commoner in DHF compared to DF, indicating that the degree of liver impairment may be related to the severity of DHF. Hyperbilirubinemia was noted in 3 (12%) DHF and 2 (8%) DF patients. The mean (range) serum bilirubin was higher in DHF [14.2(5-50) micromol/l] compared to DF [10.9(5-30) micromol/l)] (p > 0.05). Elevated levels of serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were observed more frequently in DHF (20 and 12 patients respectively) compared to DF (16 and 8 patients respectively). Nine (36%) DHF and 6 (24%) DF patients had concomitant elevation of ALT and ALP levels. The mean (range) serum ALT levels were 109.3(23-325) U/l in DHF and 90.8(13-352) U/l in DF (p > 0.05). The mean (range) serum ALP levels were 102.2(15-319) U/l in DHF and 93.3(34-258) U/l in DF (p > 0.05). The ALT and ALP levels were significantly higher in DHF patients with spontaneous bleeding than those without bleeding (p < 0.05) None of the patients developed fulminant hepatitis. The immunoregulatory cells, which include the T (CD3), B (CD 19), CD4, CD8, CD5 and natural killer (NK) cells were significantly lower in DHF compared to DF patients (p < 0.05). However, the reduction in these cell counts did not correlate with the liver dysfunction seen in DHF patients. In conclusion, hepatomegaly and liver dysfunction were commoner in DHF compared to DF.
    Matched MeSH terms: Alanine Transaminase/blood
  7. Zhang SS, Noordin MM, Rahman SO, Haron J
    Vet Hum Toxicol, 2000 Oct;42(5):261-4.
    PMID: 11003114
    The influence of copper (Cu) overload on hepatic lipid peroxidation and antioxidation defense capacity was studied by overloading rats with copper sulphate orally (500 mg Cu/kg bw) 5 d/w for 8 w. Malondialdehyde (MDA), Cu-Zn superoxide dismutase (SOD), and Se-glutathione peroxidase (GSH-Px) were measured in serum and liver homogenate at 2, 4 and 8 w of dosing. Liver Cu concentration and alanine aminotransferase (ALT) activity were also determined. As Cu loading progressed, there were multiparameter changes with significant ALT elevation, increased MDA concentrations in serum and liver homogenate, and dramatic declines of SOD and GSH-Px activities in erythrocytes and whole blood respectively, along with marked elevation of hepatic Cu in the Cu-dosed group. Excessive Cu accumulation in the liver depressed SOD and GSH-Px activities and resulted in high MDA in serum and liver homogenate due to the lipid peroxidation induced by the Cu overload.
    Matched MeSH terms: Alanine Transaminase/blood
  8. Lopez JB, Balasegaram M, Thambyrajah V, Timor J
    Malays J Pathol, 1996 Dec;18(2):95-9.
    PMID: 10879229
    This study was undertaken to see if liver function tests (LFT) served a worthwhile purpose in the investigation of hepatocellular carcinoma (HCC). Sera from 80 HCC, 76 benign liver disease (BLD) and 152 healthy adult (HA) subjects were assayed for alkaline phosphatase (ALP), gamma-glutamyltransferase (GGT), aspartate aminotransferase (AST), alanine aminotransferase and lactate dehydrogenase, bilirubin and albumin. Cut-off values were determined from the HA. ALP, GGT, AST and albumin were abnormal in about 90% of the HCC. With the exception of bilirubin, the LFT were abnormal more frequently in HCC than in chronic hepatitis and cirrhosis, the conditions which preceed it. Raised ALP in the presence of normal bilirubin was more often a feature of HCC than BLD although this relationship was not statistically significant. It seems unlikely that LFT serve a useful function in HCC.
    Matched MeSH terms: Alanine Transaminase/blood
  9. Mak JW, Navaratnam V, Grewel JS, Mansor SM, Ambu S
    Am J Trop Med Hyg, 1993 Apr;48(4):591-6.
    PMID: 8480868
    A clinical trial on the efficacy of a single oral dose of ivermectin at 20, 50, 100, and 200 micrograms/kg was carried out in 40 subjects with subperiodic Brugia malayi microfilaremia. There was no significant difference in the clearance of microfilaremia in the four treatment groups, and the lowest geometric mean microfilarial count (GMC) achieved in the 40 subjects was 8.8/ml or 8.3% of the initial count (106.1/ml), at two weeks post-treatment. The GMC started to increase at one month post-treatment and by six months was 22.2% of the initial GMC. Only 27.5%, 23.1%, 15.0%, and 18.9% of subjects were amicrofilaremic at two, four, 12, and 24 weeks post-treatment, respectively. Mild fever in 35% of the subjects was the primary side reaction and was more common in those with microfilarial counts > or = 500/ml (85.7%) than in those with counts < 500/ml (32%). The clearance of B. malayi microfilaremia by ivermectin was less rapid than that reported for Wuchereria bancrofti. The smaller number of side reactions encountered in the present study compared with those reported for bancroftian filariasis is probably related to the lower microfilarial density in the present subjects. Since ivermectin at a single oral dose of 20-200 micrograms/kg can reduce the GMC to less than 10% at two weeks and maintain it below 25% of the initial level even at six months post-treatment, it is recommended that the drug be seriously evaluated for use in the control of brugian filariasis.
    Matched MeSH terms: Alanine Transaminase/blood
  10. Tan DS, Dimitrakakis M, Zaini Rahman M, Fang R, Collett D, Ooi BG, et al.
    PMID: 3024325
    Icteric patients with clinical and biochemical evidence of liver disease, admitted into various hospitals in Malaysia, were investigated to determine the cause of their infection. Of these patients, 11.0% (16/145) were found positive for IgM anti-HAV (EIA), 4.1% (6/145) for IgM anti-HBc (EIA), 1.0% (1/102) for IgM anti-CMV (ELISA), 17.2% (16/64) for rising titres of leptospiral agglutinin, and none for heterophile antibody of EBV. Hepatitis NANB accounted for 67.9% of cases. The mean serum transaminases (ALT and AST) values in patients with hepatitis A and B were higher (more than 500IU) than in patients with leptospirosis or non-A, non-B hepatitis, whereas serum bilirubin levels were higher in patients with hepatitis A and leptospirosis than in patients with hepatitis B.
    Matched MeSH terms: Alanine Transaminase/blood
  11. Choong MF, Mak JW
    Trop. Med. Parasitol., 1991 Mar;42(1):71-2.
    PMID: 1675809
    The Presbytis cristata--Brugia malayi model, now established as a reliable non-human primate model for the experimental screening of potential filaricides, was monitored at monthly intervals for changes in the liver and renal function tests and also for alkaline phosphatase levels during infection. Animals infected with 200-400 infective larvae became patient at 50-90 days post-infection and geometric mean microfilarial counts were above 1000 per ml from the fourth month onwards. There were no significant changes in the biochemical parameters monitored throughout the period of observation. This is an important observation as any changes seen in these parameters during experimental drug studies can be attributed to drug reaction or toxicity and this will be invaluable in decision making as to drug safety.
    Matched MeSH terms: Alanine Transaminase/blood
  12. Reid HA
    Lancet, 1975 Mar 15;1(7907):622-3.
    PMID: 47960
    Among a series of 101 patients bitten by sea-snakes in Malaya in the years 1957-64, 80% were fishermen. Bathers and divers are occasionally bitten. Before sea-snake antivenom became available the mortality-rate (despite the high toxicity of sea-snake venom) was only 10%; however, of 11 with serious poisoning, 6 died. Subsequently 10 patients with serious poisoning received specific sea-snake antivenom; 2 patients, admitted moribund, temporarily improved but died, and 8 patients recovered dramatically. In serious poisoning the suitable dosage of intravenous sea-snake antivenom is 3000-10,000 units; in mild poisoning 1000-2000 units should suffice.
    Matched MeSH terms: Alanine Transaminase/blood
  13. Aurpibul L, Bunupuradah T, Sophan S, Boettiger D, Wati DK, Nguyen LV, et al.
    Pediatr Infect Dis J, 2015 Jun;34(6):e153-8.
    PMID: 25970117 DOI: 10.1097/INF.0000000000000693
    We determined the prevalence and incidence of liver dysfunction before and after initiation of combination antiretroviral therapy (cART) in the TREAT Asia Pediatric HIV Observational Database.
    Matched MeSH terms: Alanine Transaminase/blood
  14. Ranneh Y, Akim AM, Hamid HA, Khazaai H, Mokhtarrudin N, Fadel A, et al.
    Arch Immunol Ther Exp (Warsz), 2019 Dec;67(6):385-400.
    PMID: 31278602 DOI: 10.1007/s00005-019-00553-6
    Chronic subclinical systemic inflammation has a key role in stimulating several chronic conditions associated with cardiovascular diseases, cancer, rheumatoid arthritis, diabetes, and neurodegenerative diseases. Hence, developing in vivo models of chronic subclinical systemic inflammation are essential to the study of the pathophysiology and to measure the immunomodulatory agents involved. Male Sprague-Dawley rats were subjected to intraperitoneal, intermittent injection with saline, or lipopolysaccharide (LPS) (0.5, 1, 2 mg/kg) thrice a week for 30 days. Hematological, biochemical, and inflammatory mediators were measured at different timepoints and at the end of the study. The hearts, lungs, kidneys, and livers were harvested for histological evaluation. Significant elevation in peripheral blood leukocyte includes neutrophils, monocytes, and lymphocytes, as well as the neutrophils-to-lymphocyte ratio. The pro-inflammatory mediator levels [C-reactive protein, tumor necrosis factor (TNF)-α, interleukin (IL)-6, IL-1β, and IL-8] along with the biochemical profile (alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyl transferase, creatine kinase, creatinine, and urea) were increased significantly (P 
    Matched MeSH terms: Alanine Transaminase/metabolism
  15. Rupasinghe D, Kiertiburanakul S, Kamarulzaman A, Zhang F, Kumarasamy N, Chaiwarith R, et al.
    HIV Med, 2020 07;21(6):397-402.
    PMID: 31852025 DOI: 10.1111/hiv.12836
    OBJECTIVES: Early mortality among those still initiating antiretroviral therapy (ART) with advanced stages of HIV infection in resource-limited settings remains high despite recommendations for universal HIV treatment. We investigated risk factors associated with early mortality in people living with HIV (PLHIV) starting ART at low CD4 levels in the Asia-Pacific.

    METHODS: PLHIV enrolled in the Therapeutics, Research, Education and AIDS Training in Asia (TREAT Asia) HIV Observational Database (TAHOD) who initiated ART with a CD4 count  1 year were censored at 12 months. Competing risk regression was used to analyse risk factors with loss to follow-up as a competing risk.

    RESULTS: A total of 1813 PLHIV were included in the study, of whom 74% were male. With 73 (4%) deaths, the overall first-year mortality rate was 4.27 per 100 person-years (PY). Thirty-eight deaths (52%) were AIDS-related, 10 (14%) were immune reconstituted inflammatory syndrome (IRIS)-related, 13 (18%) were non-AIDS-related and 12 (16%) had an unknown cause. Risk factors included having a body mass index (BMI)  100 cells/μL: SHR 0.12; 95% CI 0.05-0.26) was associated with reduced hazard for mortality compared to CD4 count ≤ 25 cells/μL.

    CONCLUSIONS: Fifty-two per cent of early deaths were AIDS-related. Efforts to initiate ART at CD4 counts > 50 cell/μL are associated with improved short-term survival rates, even in those with late stages of HIV disease.

    Matched MeSH terms: Alanine Transaminase/metabolism
  16. Tan PC, Aziz AZ, Ismail IS, Omar SZ
    Clin Biochem, 2012 Oct;45(15):1192-6.
    PMID: 22659058 DOI: 10.1016/j.clinbiochem.2012.05.025
    OBJECTIVES: To evaluate gamma-glutamyltransferase (GGT), alanine transaminases (ALT) and aspartate transaminases (AST) levels and prevalent gestational diabetes mellitus (GDM).
    DESIGN AND METHODS: Random plasma glucose, GGT, ALT and AST and the 50-g glucose challenge test were done on antenatal women followed by diagnostic 3-point 75-g oral glucose tolerance test within two weeks. GDM was diagnosed by ADA (2011) criteria.
    RESULTS: The GDM rate was 12.2% (319/2610). Mean GGT level was higher in GDM women, 18 ± 12 vs. 16 ± 11 IU/L; P=0.03. The risk for GDM was higher for women in the highest GGT quartile band compared to the lowest: RR 1.35 95%CI 1.0-1.8; P=0.04. However, after adjustment for confounders, GGT was no longer associated with GDM. There was no correlation between ALT and AST levels and GDM.
    CONCLUSIONS: Liver transaminases do not predict GDM in contrast to type 2 diabetes.
    Matched MeSH terms: Alanine Transaminase/blood*
  17. Amzar N, Iqbal M
    J Environ Pathol Toxicol Oncol, 2017;36(4):293-307.
    PMID: 29431062 DOI: 10.1615/JEnvironPatholToxicolOncol.2017019824
    Liver diseases still represents a major health burden worldwide. Moreover, medicinal plants have gained popularity in the treatment of several diseases, including liver disease. Clidemia hirta possesses many medicinal properties for healing several diseases and for health maintenance. However, the hepatoprotective effects and antioxidative potential of C. hirta have not been fully investigated. In the present study, we evaluated the hepatoprotective and antioxidative potential of C. hirta against carbon tetrachloride (CCl4)-induced liver injuries and oxidative damage in a murine model. Various biochemical changes associated with liver damage and oxidative stress were measured. The mice were pretreated for 14 consecutive days with aqueous extract of C. hirta at selected doses (150 mg/kg body weight [b.w.], 300 mg/kg b.w. and 600 mg/kg b.w.) followed by two doses of CCl4 (1.0 mL/kg b.w.) orally on days 14 and 15. All animals were sacrificed 24 hours after the last dose of CCl4 or saline. Blood and liver tissues were taken quickly for biochemical and histopathological studies to assess the derangement in the functioning of liver. The development of oxidative stress was observed through the escalation of hepatic lipid peroxidation, depletion of glutathione, and reduced antioxidant enzymes (glutathione peroxidase, glutathione reductase, catalase, glutathione S-transferase and quinone reductase). Hepatic damage was evaluated by measuring serum transaminase (ALT and AST). In addition, CCl4-induced hepatic damage was further evaluated using histopathological assessments. However, most of these changes were dependently ameliorated by the pretreatment of mice with a C. hirta dose. These results indicate that the hepatoprotective effect of C. hirta might be due to its antioxidant and free-radical scavenging properties.
    Matched MeSH terms: Alanine Transaminase/blood
  18. Nájera F, Hearn AJ, Ross J, Nathan S, Revuelta L
    Vet Res Commun, 2014 Sep;38(3):265-9.
    PMID: 24839119 DOI: 10.1007/s11259-014-9605-2
    Box-traps for capturing wild cats are widely used by researchers since it is one of the most effective methods for trapping these species. Although they are extensively utilised, the effects on the physiology of trapped felids remain unclear. Researchers frequently make judgements regarding the safety of such capture devices by examination of external injuries but often fail to take into consideration other physiological parameters. To assess the effects of capture events on selected serum biochemistry values of free-ranging Bornean leopard cats (Prionailurus bengalensis borneoensis) six free-ranging leopard cats (four males, two females) were trapped by using box-traps in Sabah, Malaysian Borneo. Blood was collected by jugular venipucture after chemical immobilization with a mixture of tiletamine and zolazepam. Blood was analysed for 17 serum biochemistry parameters. The most consistent and significantly higher value found in both sexes was aspartate aminotransferase (AST), followed by high mean value of alanine aminotransferase (ALT). Both mean values exceeded the upper limit of the reference range for captive leopard cats. These results demonstrate that captured leopard cats by box-traps undergo physical exertion and consequently some type of muscle injury/damage. Researchers and wildlife managers should be aware of the physiological response of trapped felids when using box-traps. Devices that facilitate the prompt removal of leopard cats from the traps would be useful for researchers to avoid further damage while live trapping this species.
    Matched MeSH terms: Alanine Transaminase/blood
  19. Tang SGH, Sieo CC, Ramasamy K, Saad WZ, Wong HK, Ho YW
    BMC Vet Res, 2017 Aug 17;13(1):248.
    PMID: 28814309 DOI: 10.1186/s12917-017-1160-y
    BACKGROUND: The increasing trend of ban on the use of antibiotic growth promoters (AGPs) across the globe in the poultry industry has led to a growing need for alternatives to AGPs. Prebiotic, probiotic and their combination as a synbiotic have been considered as potential alternatives. This study aimed to investigate the effects of a prebiotic (isomaltooligosaccharide, IMO), a probiotic (PrimaLac®), and their combination (synbiotic) on hen performance, biochemical and haematological responses, and relative organ weights from 20 to 52 weeks of age.

    RESULTS: Supplementation of 1% IMO (PRE), 0.1% PrimaLac® (PRO) and 1% IMO + 0.1% PrimaLac® (SYN) improved (P 

    Matched MeSH terms: Alanine Transaminase/blood
  20. Rasineni GK, Loh PC, Lim BH
    Biochim Biophys Acta Gen Subj, 2017 Feb;1861(2):79-85.
    PMID: 27816753 DOI: 10.1016/j.bbagen.2016.10.027
    BACKGROUND: Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is the chloroplast enzyme that fixes CO2 in photosynthesis, but the enzyme also fixes O2, which leads to the wasteful photorespiratory pathway. If we better understand the structure-function relationship of the enzyme, we might be able to engineer improvements. When the crystal structure of Chlamydomonas Rubisco was solved, four new posttranslational modifications were observed which are not present in other species. The modifications were 4-hydroxylation of the conserved Pro-104 and 151 residues, and S-methylation of the variable Cys-256 and 369 residues, which are Phe-256 and Val-369 in land plants. Because the modifications were only observed in Chlamydomonas Rubisco, they might account for the differences in kinetic properties between the algal and plant enzymes.

    METHODS: Site-directed mutagenesis and chloroplast transformation have been used to test the essentiality of these modifications by replacing each of the residues with alanine (Ala). Biochemical analyses were done to determine the specificity factors and kinetic constants.

    RESULTS: Replacing the modified-residues in Chlamydomonas Rubisco affected the enzyme's catalytic activity. Substituting hydroxy-Pro-104 and methyl-Cys-256 with alanine influenced Rubisco catalysis.

    CONCLUSION: This is the first study on these posttranslationally-modified residues in Rubisco by genetic engineering. As these forms of modifications/regulation are not available in plants, the modified residues could be a means to modulate Rubisco activity.

    GENERAL SIGNIFICANCE: With a better understanding of Rubisco structure-function, we can define targets for improving the enzyme.

    Matched MeSH terms: Alanine/genetics
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