Modification of rabbit muscle aldolase in Vivo and in Vitro

✍ Scribed by C. Y. Lai; B. L. Horecker

• Publisher: John Wiley and Sons
• Year: 1970
• Tongue: English
• Weight: 713 KB
• Volume: 76
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.1040760316

✦ Synopsis

Abstract

Rabbit muscle aldolase in situ appears to undergo several modification reactions. One of these, specific deamidation of an asparagine residue near the COOH‐terminus, appears to account for the presence of two types of subunits in the enzyme isolated from the muscle of adult rabbits. Evidence for a second modification is the presence of approximately one equivalent of organic phosphorus in the crystalline enzyme preparations. The presence of this phosphate group may be related to the incomplete release of COOH‐terminal tyrosine residues from the enzyme protein with carboxypeptidase. Two reactions with substrate, both leading to the incorporation of organic phosphorus, have been demonstrated in vitro. A reaction with glyceraldehyde 3‐phosphate or erythrose 4‐phosphate leads to loss of catalytic activity and change in the susceptibility of COOH‐terminus to carboxypeptidase. The other reaction, with fructose 1,6‐diphosphate at low concentration, does not affect the activity of the enzyme, nor its susceptibility towards the action of carboxypeptidase. Either or both of these may be related to the changes which appear to occur during the life of the enzyme in vivo.