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Titolo:
MODIFICATION OF CARBONIC-ANHYDRASE-III ACTIVITY BY PHOSPHATE AND PHOSPHORYLATED METABOLITES
Autore:
SHELTON JB; CHEGWIDDEN WR;
Indirizzi:
SHEFFIELD HALLAM UNIV,DIV BIOMED SCI,POND ST SHEFFIELD S1 1WB S YORKSHIRE ENGLAND SHEFFIELD HALLAM UNIV,DIV BIOMED SCI SHEFFIELD S1 1WB S YORKSHIRE ENGLAND SHEFFIELD HALLAM UNIV,HLTH RES INST SHEFFIELD S1 1WB S YORKSHIRE ENGLAND
Titolo Testata:
Comparative biochemistry and physiology. Part A, Physiology
fascicolo: 4, volume: 114, anno: 1996,
pagine: 283 - 289
SICI:
1096-4940(1996)114:4<283:MOCABP>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
MAGNETIC-RESONANCE SPECTROSCOPY; SKELETAL-MUSCLE FIBERS; CATALYTIC PROPERTIES; PROTON-TRANSFER; ENHANCEMENT; INHIBITION; ACTIVATION; PURIFICATION; SULFONAMIDES; REPLACEMENT;
Keywords:
ARGININE MODIFICATION; ATP; BUTANEDIONE; CARBONIC ANHYDRASE III; ENZYME REGULATION; MUSCLE METABOLISM; PHOSPHATE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
55
Recensione:
Indirizzi per estratti:
Citazione:
J.B. Shelton e W.R. Chegwidden, "MODIFICATION OF CARBONIC-ANHYDRASE-III ACTIVITY BY PHOSPHATE AND PHOSPHORYLATED METABOLITES", Comparative biochemistry and physiology. Part A, Physiology, 114(4), 1996, pp. 283-289

Abstract

Chicken carbonic anhydrase III (CA III) is potently activated by phosphate (k(cat)/K-M is increased for bicarbonate dehydration from 0.6 x 10(4) M(-1)s(-1) to 1.2 X 10(4) M(-1)s(-1) in 10 mM phosphate). The presence of phosphate both reduces K-M and increases k(cat). Activation is also evident when the enzyme is pretreated by incubating with phosphate and is subsequently assayed at negligibly low phosphate concentration. The dissociation of the phosphate-enzyme complex is slow (k(d) =0.084 min(-1)) suggesting that activation in vivo may be sustained through fluctuating phosphate levels. A similar enhancement may also be achieved by various phosphorylated metabolites at concentrations within homeostatic physiological levels. Modification of active site arginine residues by 2,3-butanedione (MD) yielded similar results to those obtained by pretreatment with phosphate, suggesting a common feature ofthe activating mechanism. Both DD-modified and phosphate-modified enzyme could be further activated by augmenting the assay mixture with phosphate. Two mechanisms of phosphate enzyme interaction are inferred. Phosphate has no significant effect on the esterase activity, thus supporting the premise that the esterase and CO2 hydration sites are physically separated in the CA III isoenzymes.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 24/11/20 alle ore 14:12:00