Hybrid aspartate transcarbamoylase containing cross-linked subunits.

W. W. Chan, Caroline Enns

Research output: Contribution to journalArticle

9 Citations (Scopus)

Abstract

The role of conformational changes and subunit interactions in the allosteric mechanism of aspartate transcarbamoylase was evaluated by studying hybrid enzyme molecules containing cross-linked subunits. Native enzyme was cross-linked with tartryl diazide in the presence and absence of substrate analogues. The two types of modified enzyme derivatives were each dissociated into catalytic (c3) and regulatory (r2) subunits. Hybrids were constructed with modified catalytic subunits and unmodified regulatory subunits of vice versa. Subunits from different derivatives also formed hybrids. All hybrids containing cross-linked catalytic subunits showed hyperbolic substrate saturation curves while cross-linked in the regulatory subunit alone did not abolish cooperativity. The type of cross-linked in the catalytic subunit had a decisive influence on the substrate affinity of the hybrid as well as its response to the allosteric effectors ATP and CTP. However many effects were also dependent on the presence of regulatory subunits. The results implicate a substantial conformational change in the catalytic subunit upon substrate binding and suggest an important role for the c-r interaction in the allosteric mechanism.

Original languageEnglish (US)
Pages (from-to)461-468
Number of pages8
JournalCanadian Journal of Biochemistry
Volume59
Issue number6
StatePublished - Jun 1981
Externally publishedYes

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Aspartic Acid
Catalytic Domain
Enzymes
Cytidine Triphosphate
Adenosine Triphosphate

ASJC Scopus subject areas

  • Medicine(all)

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Hybrid aspartate transcarbamoylase containing cross-linked subunits. / Chan, W. W.; Enns, Caroline.

In: Canadian Journal of Biochemistry, Vol. 59, No. 6, 06.1981, p. 461-468.

Research output: Contribution to journalArticle

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