HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kantrowitz, E. R. Articles by Lipscomb, W. N. Search for Related Content PubMed PubMed Citation Articles by Kantrowitz, E. R. Articles by Lipscomb, W. N. Social Bookmarking                      What's this?

JBC, Vol. 252, Issue 9, 2873-2880, May, 1977

Functionally important arginine residues of aspartate transcarbamylase

E. R. Kantrowitz and W. N. Lipscomb

The reaction of phenylglyoxal with aspartate transcarbamylase and its isolated catalytic subunit results in complete loss of enzymatic activity (Kantrowitz, E. R., and Lipscomb, W. N. (1976) J. Biol. Chem. 251, 2688-2695). If N-(phosphonacetyl)-L-aspartate is used to protect the active site, we find that phenylglyoxal causes destruction of the enzyme's susceptibility to activation by ATP and inhibition by CTP. Furthermore, CTP only minimally protects the regulatory site from reaction with this reagent. The modified enzyme still binds CTP although with reduced affinity. After reaction with phenylglyoxal, the native enzyme shows reduced cooperativity. The hybrid with modified regulatory subunits and native catalytic subunits exhibits slight heterotropic or homotropic properties, while the reverse hybrid, with modified catalytic subunits and native regulatory subunits, shows much reduced homotropic properties but practically normal heterotropic interactions. The decrease in the ability of CTP to inhibit the enzyme correlates with the loss of 2 arginine residues/regulatory chain (Mr = 17,000). Under these reaction conditions, 1 arginine residue is also modified on each catalytic chain (Mr = 33,000). Reaction rate studies of p-hydroxymercuribenzoate, with the liganded and unliganded modified enzyme suggest that the reaction with phenylglyoxal locks the enzyme into the liganded conformation. The conformational state of the regulatory subunit is implicated as having a critical role in the expression of the enzyme's heterotropic and homotropic properties.
CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				S. Takazaki, Y. Abe, D. Kang, C. Li, X. Jin, T. Ueda, and N. Hamasaki The functional role of arginine 901 at the C-terminus of the human anion transporter band 3 protein. J. Biochem., May 1, 2006; 139(5): 903 - 912. [Abstract] [Full Text] [PDF]