Evidence for tissue specific alterations in Zn2+-induced conformational changes in fructose-bisphosphatase of senescent rats.
In vitro studies on Zn2+-induced modulations in certain allosteric control of fructose-1,6-bisphosphatase (FBPase: EC 3.1.3.11), isolated from liver and muscle of 28- and 97-wk old rats were carried out in parallel. Similar chromatographic elution on ion-exchanger and electrophoretic mobility on polyacrylamide gels revealed similarity in charge and molecular size of the enzyme proteins from the two ages of rats. Regarding Zn2+ induced modulations, almost all the parameters used did not show any age-dependent significant alteration with liver enzyme. However, in case of muscle FBPase, apart from a significant increase in Ki for ZnCl2, Zn2+-induced modulations in substrate affinity and AMP inhibition were observed to be altered markedly with the enzyme of 97-wk-old rats in comparison to that of 28-wk-old rats. Thus, it suggests age-associated alterations in Zn2+-mediated conformational modification in the muscle enzyme. This has been further supported by tissue-specific usual pattern of substrate affinity in the absence of Zn2+ and exhibition of normal AMP inhibition after replacement of Zn2+ by EDTA. Such age-dependent changes induced by Zn2+ in muscle FBPase may be of high physiological significance with advancing age of the animal.
Trigun
S K
SK
Centre of Advanced Study in Zoology, Banaras Hindu University, Varanasi, India.
Singh
S N
SN
D000375:Aging; D000818:Animals; D002712:Chlorides / Q000494:pharmacology*; D003600:Cytosol / Q000201:enzymology; D006597:Fructose-Bisphosphatase / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000201:enzymology / Q000254:growth & development*; D024510:Muscle Development; D009132:Muscles / Q000201:enzymology; D011487:Protein Conformation; D051381:Rats; D011919:Rats, Inbred Strains; D015032:Zinc / Q000494:pharmacology*; D017967:Zinc Compounds
D002712:Chlorides; D017967:Zinc Compounds; C016837:zinc chloride; D006597:Fructose-Bisphosphatase; D015032:Zinc