Publisher Summary This chapter explores that the changes that take place in the protein molecules during denaturation constitute one of the most interesting and complex classes of reactions that can be found either in nature or in the laboratory These reactions are important because of the information they can provide about the more intimate details of protein structure and function They are also significant because they challenge the chemist with a difficult area for the application of chemical principles The chapter reviews that the denaturation is a process in which the spatial arrangement of the polypeptide chains within the molecule is changed from that typical of the native protein to a more disordered arrangement The chapter also discusses the classification of protein structures: primary, secondary, and tertiary structures The primary structure is that expressed by the structural chemical formula and depends entirely on the chemical valence bonds that the classical organic chemist would write down for the protein molecule The secondary structure is the configuration of the polypeptide chain that results from the satisfaction of the hydrogen bonding potential between the peptide N-H and C=O groups The tertiary structure is the pattern according to which the secondary structures are packed together within the native protein molecule The term “denaturation” as used in this chapter is indented to include changes in both the secondary and tertiary structures

Some factors in the interpretation of protein denaturation.

Publisher Summary This chapter discusses the assay of catalases and peroxidases are: (1) catalase assay by disappearance of peroxide; (2) method for crude cell extracts; (3) direct spectrophotometric assay of catalase and peroxidase in cells and tissues; and (4) peroxidase assay by spectrophotometric measurements of the disappearance of hydrogen donor or the appearance of their colored oxidation products. Two methods are described for the catalase assay by disappearance of peroxide are: ultraviolet spectrophotometry and permanganate titration. Ultraviolet spectrophotometryis a method devised, on the basis of the absorption curves for peroxide solutions, for determining the activity of catalase by direct measurements of the decrease of light absorption in the region 230 to 250 mμ caused by the decomposition of hydrogen peroxide by catalase. In the case of method for crude cell extracts, oxygen evolution caused by the decomposition of hydrogen peroxide is measured with the conventional manometric technique. Peroxidase assay by spectrophotometric measurements of the disappearance of hydrogen donor or the appearance of their colored oxidation products includes the guaiacol test and the pyrogallol test.

The assay of catalases and peroxidases.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1538-7836.2005.01365.x

Fibrinogen and fibrin structure and functions.

A theory of gel filtration and its exeperimental verification

The structural and mechanical properties of gels formed from biopolymers are discussed both in terms of the techniques used to characterise these systems, and in terms of the systems themselves The techniques included are spectroscopic, chiroptical and scattering methods, optical and electron microscopy, thermodynamic and kinetic methods and rheological characterisation The systems considered are presented in order of increasing complexity of secondary, tertiary and quaternary structure, starting with gels which arise from essentially ‘disordered’ biopolymers via formation of ‘quasicrystalline’ junction zones (eg gelatin, carrageenans, agarose, alginates etc), and extending to networks derived from globular and rod-like species (fibrin, globular proteins, caseins, myosin) by a variety of crosslinking mechanisms Throughout the text, efforts are made to pursue the link (both from experiment and from theory) between the structural methods and mechanical measurements As far as we are aware this is the first major Review of this area since that of J D Ferry in 1948 — The interest shown by polymer physicists in more complex biochemical systems, and the multi-disciplinary approaches now being applied in this area, make the format adopted here, in our opinion, the most logical and appropriate

Structural and mechanical properties of biopolymer gels

Publisher Summary The thrombin-induced conversion of fibrinogen to fibrin that is the primary subject of this review is essentially the final stage in the complex series of processes involved in blood coagulation. Fibrinogen exists in normal blood, while thrombin is present as its precursor prothrombin. The coagulation process consists of the conversion of prothrombin to thrombin and of the subsequent action of thrombin on fibrinogen to produce fibrin. In the fibrinogen-fibrin conversion fibrinogen, already a high polymer of many amino acids is converted to an even higher polymeric form or coagulum, the fibrin clot. Prothrombin can be converted to thrombin in a series of highly complex, and as yet not well understood, reactions. The chapter explores four of the processes by which the conversion of prothrombin to thrombin takes place. These are (1) activation by citrate, (2) activation by calcium ions, Ac-globulin and thromboplastin, (3) activation by calcium ions, platelets and thromboplastin, and (4) activation by trypsin. The chapter concludes by addressing the various problems of current interest in protein chemistry, which appear in the study of the fibrinogen-fibrin conversion. The first step is an example of a limited proteolysis by a protease of curious specificity. This proteolysis may turn out to be one of the first illustrations of the existence of “strong” peptide bonds in proteins. Further, it offers a nice illustration of the phenomenon of unmasking or activation in biological systems. The second step involves protein-protein associations with unequal association constants. The last step may involve gel formation or crystallization.

The Fibrinogen-Fibrin Conversion1

Thermodynamic Considerations of Protein Reactions.1,2 I. Modified Reactivity of Polar Groups

Thermodynamic Considerations of Protein Reactions.1,2 II. Modified Reactivity of Primary Valence Bonds

Preparation and characterization of a fully iodinated insulin derivative.

Crystalline catalase from beef erythrocytes.

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