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Evaluation of the Interplay Between the Complement Protein C1q and Hyaluronic Acid in Promoting Cell Adhesion
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Complement factor D, a novel serine protease

J E Volanakis1, S V Narayana

  • 1Department of Medicine, University of Alabama at Birmingham 35294, USA. jvolanakis@medinfo.dom.uab.edu

Protein Science : a Publication of the Protein Society
|April 1, 1996
PubMed
Summary
This summary is machine-generated.

Factor D, a unique serine protease, is regulated by reversible conformational changes induced by its substrate, C3bB, not by cleavage or serpins. This mechanism controls its catalytic activity through structural alterations.

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Area of Science:

  • Biochemistry
  • Enzymology
  • Protease Regulation

Background:

  • Factor D is a serine protease with unique regulatory properties.
  • Unlike other serine proteases, Factor D does not require enzymatic cleavage for activation or serpin for inactivation.
  • Its activity is controlled by a novel mechanism involving reversible conformational changes.

Purpose of the Study:

  • To elucidate the unique mechanism regulating Factor D activity.
  • To understand how conformational changes influence Factor D's catalytic function.
  • To identify structural determinants responsible for Factor D's unique properties.

Main Methods:

  • Analysis of Factor D's unique regulatory mechanism.
  • Investigating conformational changes induced by the natural substrate C3bB.
  • Utilizing mutational studies to define structural determinants.

Main Results:

  • Factor D activity is regulated by reversible conformational changes, not cleavage or serpins.
  • These changes are induced by the substrate C3bB.
  • Mutational studies identified key structural features contributing to Factor D's atypical conformations and low reactivity with synthetic esters.

Conclusions:

  • Factor D employs a unique substrate-induced conformational change mechanism for activity regulation.
  • This mechanism involves atypical conformations of the catalytic triad and substrate binding sites.
  • Structural determinants of Factor D underlie its distinct catalytic properties and substrate interactions.