This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Agee, C. C. Articles by Airth, R. L. Search for Related Content PubMed PubMed Citation Articles by Agee, C. C. Articles by Airth, R. L.

Reversible Inactivation of Thiaminase I of Bacillus thiaminolyticus by Its Primary Substrate, Thiamine

^a Cell Research Institute, University of Texas, Austin, Texas 78712

ABSTRACT

Thiaminase I of Bacillus thiaminolyticus is reversibly inactivated when it is incubated with its primary substrate, thiamine, or with one of several structural analogues of thiamine in the absence of an acceptor base. The inactivation reaction is pH and temperature dependent and is stochiometric with respect to thiamine and thiaminase I concentrations. One molecule of thiamine is cleaved for each molecule of enzyme inactivated. Inactivation is prevented or reversed by sulfhydryl-reducing agents. Active or reactivated thiaminase I migrate as a single band in polyacrylamide electrophoresis gels. Inactive thiaminase I appears to migrate as two separate bands. Active, inactive, and reactivated thiaminase I are immunologically similar. A possible mechanism for the inactivation of thiaminase I by its substrate is discussed.

¹ Present address: Department of Biochemistry, University of Illinois, Urbana, Ill. 61801.

² Deceased.