Protein Disulfida Isomerase: Pembentuk Ikatan Disulfida dan Pelipatan Protein
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Date
2000
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Balai Penelitian Bioteknologi Tanaman Pangan
Abstract
Protein Disulfide Isomerase: Protein Disulfide Bond Formation and Protein Folding.
Jumiarti Agus. Protein is synthesized by the ribosomes in vivo as linear polypeptide chains and they have to fold to their final conformations either during or after its biosynthesis. There are two proteins involved in the protein folding process, namely molecular chaperones and catalysts. Protein disulfide isomerase (PDI, E.C. 5.3.4.1) is an enzyme that plays a role in protein disulfide bond formation and protein folding. PDI have been isolated from various organisms, such as mammalian livers, plant, green algae, and yeast {Saccharomyces cerevisiae). PDI enzymes that were isolated from the various organisms had similarities, they were homodimer enzymes. Each monomer had two active site domains (a and a') that contained a cysteine-glysine-histidine-cysteine (C-G-H-C) sequence. PDI gene from S. cerevisiae is haplo-lethal, but up to date the essential amino acids involved in the PDI activity and viability are not known. PDI is a multifunctional protein that acts as a p sub-unit of prolyl-4 hydroxylase, a component of microsomal triglyseride transfer protein (MTP), an enzyme bonding peptide or protein, and as chaperones. A number of proteins that have similar function to that of PDI had been identified, particularly around the active site C-G-H-C sequence. These
proteins were thioreduxin, DsbA, and Eugip.
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Keywords
Protein disulfide isomerase, formation of disulfide bond, protein folding