Related Experiment Video

Updated: Jul 13, 2026

Coupled Assays for Monitoring Protein Refolding in Saccharomyces cerevisiae
13:52

Coupled Assays for Monitoring Protein Refolding in Saccharomyces cerevisiae

Published on: July 9, 2013

Structural changes accompanying enzymatic activation of human Hageman factor

S D Revak, C G Cochrane, A R Johnston

    The Journal of Clinical Investigation
    |September 1, 1974
    PubMed

    The structure of Hageman factor, isolated from human plasma, was analyzed before and after enzymatic activation. The purified molecule is a single polypeptide chain of 80,000 molecular weight (mol wt) sedimenting at 4.5S. An amino acid analysis has been performed. The concentration of Hageman factor in normal human plasma was found to be 29 mug/ml with variation between individuals ranging from 15 to 47 mug/ml. Treatment of the molecule with kallikrein, plasmin, or trypsin resulted in cleavage at two primary sites, yielding fragments of 52,000, 40,000, and 28,000 mol wt. No further changes occurred in the fragments with subsequent reduction. Prekallikrein-activating ability was associated exclusively with the 28,000 moiety.

    More Related Videos

    Fluorescence-based Monitoring of PAD4 Activity via a Pro-fluorescence Substrate Analog08:37

    Fluorescence-based Monitoring of PAD4 Activity via a Pro-fluorescence Substrate Analog

    Published on: November 5, 2014

    Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes09:42

    Unraveling Entropic Rate Acceleration Induced by Solvent Dynamics in Membrane Enzymes

    Published on: January 16, 2016

    Related Concept Videos

    Enzymes02:34

    Enzymes

    Inside living organisms, enzymes act as catalysts for many biochemical reactions involved in cellular metabolism. The role of enzymes is to reduce the activation energies of biochemical reactions by forming complexes with its substrates. The lowering of activation energies favor an increase in the rates of biochemical reactions.
    Enzyme deficiencies can often translate into life-threatening diseases. For example, a genetic abnormality resulting in the deficiency of the enzyme G6PD...
    Histone Modification02:32

    Histone Modification

    The histone proteins have a flexible N-terminal tail extending out from the nucleosome. These histone tails are often subjected to post-translational modifications such as acetylation, methylation, phosphorylation, and ubiquitination. Particular combinations of these modifications form “histone codes” that influence the chromatin folding and tissue-specific gene expression.
    Acetylation
    The enzyme histone acetyltransferase adds acetyl group to the histones. Another enzyme, histone deacetylase,...
    Enzymes and Activation Energy01:13

    Enzymes and Activation Energy

    The activation energy (or free energy of activation), abbreviated as Ea, is the small amount of energy input necessary for all chemical reactions to occur. During chemical reactions, certain chemical bonds break, and new ones form. For example, when a glucose molecule breaks down, bonds between the molecule's carbon atoms break. Since these are energy-storing bonds, they release energy when broken. However, the molecule must be somewhat contorted to get into a state that allows the bonds to...
    Introduction to Mechanisms of Enzyme Catalysis01:13

    Introduction to Mechanisms of Enzyme Catalysis

    For many years, scientists thought that enzyme-substrate binding took place in a simple "lock-and-key" fashion. This model stated that the enzyme and substrate fit together perfectly in one instantaneous step. However, current research supports a more refined view scientists call induced fit. The induced-fit model expands upon the lock-and-key model by describing a more dynamic interaction between enzyme and substrate. As the enzyme and substrate come together, their interaction causes a mild...
    Protein Denaturation01:28

    Protein Denaturation

    The function of proteins depends on their native three-dimensional structure, which is dictated by the amino acid sequence of the specific protein. Folding of the polypeptide chain takes place under specific conditions that energetically favor the folded conformation. In contrast, protein denaturation occurs spontaneously under unfavorable conditions that disrupt the integrity of the folded conformation. Thus, the chemical and physical environment of a protein, such as significant changes in pH...
    Enzymes and Activation Energy01:13

    Enzymes and Activation Energy

    The activation energy (or free energy of activation), abbreviated as Ea, is the small amount of energy input necessary for all chemical reactions to occur. During chemical reactions, certain chemical bonds break, and new ones form. For example, when a glucose molecule breaks down, bonds between the molecule's carbon atoms break. Since these are energy-storing bonds, they release energy when broken. However, the molecule must be somewhat contorted to get into a state that allows the bonds to...