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Structure and formation of microplasmin
1Biochemistry Department, Medical College, National Cheng-Kung University, Taiwan, Republic of China.
Abstract:
The structure of human microplasmin, prepared from plasmin in alkaline solution, has been studied. Microplasmin consists of two polypeptide chains connected by disulfide bonds. One polypeptide is the B chain of plasmin consisting of 230 amino acids, and the other peptide is the COOH-terminal portion of the A chain of plasmin consisting of 31 amino acid residues. Microplasmin has a molecular weight of 28,635, calculated from its primary sequence. It is slightly more positively charged than plasminogen and is a more hydrophobic molecule. The proposed scheme for the formation of microplasmin involves autolysis at specific peptide bonds and scrambling of especially sensitive disulfide bonds in alkaline solution.
Insights
Researchers elucidated the structure of human microplasmin, revealing it comprises two polypeptide chains. This study details its composition, molecular weight, and charge properties, offering insights into its formation.
Area of Science:
- Biochemistry
- Molecular Biology
- Protein Chemistry
Background:
- Plasmin is a key enzyme in fibrinolysis.
- Understanding plasmin derivatives like microplasmin is crucial for studying clot lysis.
- Previous structural data on microplasmin was limited.
Purpose of the Study:
- To determine the detailed structure of human microplasmin.
- To characterize the polypeptide composition and molecular properties of microplasmin.
- To propose a mechanism for microplasmin formation.
Main Methods:
- Preparation of human microplasmin from plasmin in alkaline solution.
- Analysis of polypeptide chain composition.
- Calculation of molecular weight from primary sequence.
- Assessment of charge and hydrophobicity.
Main Results:
- Microplasmin consists of two polypeptide chains linked by disulfide bonds.
- One chain is the plasmin B chain (230 amino acids); the other is the COOH-terminal part of the plasmin A chain (31 amino acids).
- Microplasmin has a molecular weight of 28,635 Da, is more positively charged, and more hydrophobic than plasminogen.
Conclusions:
- The structure of human microplasmin has been elucidated.
- Microplasmin formation likely involves autolysis and disulfide bond scrambling in alkaline conditions.
- These findings contribute to the understanding of plasmin structure-function relationships.