About: Denaturation (biochemistry) is a research topic. Over the lifetime, 7982 publications have been published within this topic receiving 328367 citations.
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TL;DR: 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.
Abstract: 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
TL;DR: Crystalline soy protein when denatured is readily digestible by pepsin, and less readily by chymotrypsin and by trypsin, which results in a proportional gain in the inhibiting activity.
Abstract: A study has been made of the general properties of crystalline soybean trypsin inhibitor. The soy inhibitor is a stable protein of the globulin type of a molecular weight of about 24,000. Its isoelectric point is at pH 4.5. It inhibits the proteolytic action approximately of an equal weight of crystalline trypsin by combining with trypsin to form a stable compound. Chymotrypsin is only slightly inhibited by soy inhibitor. The reaction between chymotrypsin and the soy inhibitor consists in the formation of a reversibly dissociable compound. The inhibitor has no effect on pepsin. The inhibiting action of the soybean inhibitor is associated with the native state of the protein molecule. Denaturation of the soy protein by heat or acid or alkali brings about a proportional decrease in its inhibiting action on trypsin. Reversal of denaturation results in a proportional gain in the inhibiting activity. Crystalline soy protein when denatured is readily digestible by pepsin, and less readily by chymotrypsin and by trypsin. Methods are given for measuring trypsin and inhibitor activity and also protein concentration with the aid of spectrophotometric density measurements at 280 mmicro.
TL;DR: The chapter discusses the stability of proteins and presents the results obtained on small compact globular proteins, which represent one single cooperative system, and the temperature-induced changes in protein, denaturational and predenaturational changes inprotein, thermodynamics of protein unfolding, and thermodynamic properties of protein.
Abstract: Publisher Summary The chapter discusses the stability of proteins and presents the results obtained on small compact globular proteins, which represent one single cooperative system. Protein is a cooperative system and behaves in an all-or-none fashion. Sharp changes in the properties of a protein do not mean anything in themselves because sequential multistep transitions exhibit the same sharp sigmoidal changes in the observed parameters. The problem of stability of native proteins is closely connected with the problem of protein denaturation, as stability can be judged only by breaking the native structure—that is, denaturing protein by various treatments. The pH of the solution is one of the most important factors determining the state of a protein. Potentiometric titration of protein revealed that smooth changes are connected with the titration of groups with a pK not very different from that of free amino acids, while the gross conformational changes associated with pH denaturation are accompanied by the unmasking of buried groups. The chapter also discusses the temperature-induced changes in protein, denaturational and predenaturational changes in protein, thermodynamics of protein unfolding, and thermodynamic properties of protein.
TL;DR: This chapter reviews theoretical models that might be constructed and equations that may be derived from them to understand the process of protein denaturation and finds that they can be predicted semiquantitatively.
Abstract: Publisher Summary This chapter reviews theoretical models that may be constructed and equations that may be derived from them to understand the process of protein denaturation. Given that the native state is stable under physiological conditions, the question arises whether the effects of environmental changes on the equilibrium between native and denatured states can be predicted, so as to account for the loss of stability of the native state and the appearance of different denatured states under specified conditions. This question involves not the absolute values for the free energies and other thermodynamic parameters for denaturation processes, but the changes in these parameters, along with changes in environmental variables. These changes can be predicted semiquantitatively. Furthermore, one can account both for the products formed under different conditions and for the character of the transitions from native to denatured state, at least for the simple proteins that have been studied in detail.
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