Thermal stability proteolytic enzymes

The stability of both the wild-type and mutant proteins is expressed as the melting temperature, Tm, which is the temperature at which 50% of the enzyme is denatures during irreversible heat denaturation. To prevent the self-digestion of penicillolysin, heat treatment was carried out at pH 5.0 because the proteolytic activity is substantially reduced at this pH and the active form of the enzyme is stable. For the wild-type enzyme and the three mutants, the thermal stabilities and the 7m changes were assayed at pH 5.0 by measuring the far-UV CD spectrum at 222 nm as a function of temperature. For the wild-type penicillolysin, the Tm... 

Other measures of protein flexibility have been found to correlate with thermal stability. One is resistance to proteolysis (Daniel et al., 1982 Fontana, 1988). Another is the quenching of buried tryptophan fluorescence by acrylamide, used in a study by Varley and Pain (1991). Both these processes are mediated by the same combination of local and global unfolding events that determine rates of hydrogen exchange. Their rates will depend on the ability of another molecule, acrylamide or a proteolytic enzyme, to penetrate into normally buried regions of the protein in order to either quench fluorescence or cleave peptide bonds. 

Thermal Stability. Increased catalytic efficiency at low temperatures is associated often with a decrease in thermal stability (41). Proteolytic enzymes from the pyloric caeca of cod, herring, and mackerel are more heat labile than bovine trypsin (42) the thyroid protease of burbot from cold waters had lower thermal stability than that from burbot in a warmer habitat (43). The half-life of myofibrillar ATPase at 37°C averages 1 min for the enzyme from Antarctic Ocean fish species, 70 min for the enzyme from fish species in the Indian Ocean, and 600 min for the enzyme from East African hot spring fish (33). 

Thermolysin. Bacillus thermoproteolyticus neu -tral proteinase, E.C. 3.4.24.4. Proteolytic enzyme of mol wt 37,500 that hydrolyzes protein bonds on the JV-terminal side of hydrophobic amino acid residues. Contains a zinc atom essentia] for activity and four Ca2+ ioos essentia] for thermal and conformational stability. Isolo from Bacillus thermopro-leolyticus S. Endo, J. Ferment. Technol. 40, 346 (1962). Properties and amino acid composition Y. Ohta ei of., J. Biol. Chem. 241, 5919 (1966). Site of enzymatic hydrolysis Y. Ohta, Y. Ogura, J. Biochem. 58, 607 (1965). Substrate specificity studies H. Matsubara ei al.. Biochem. Biophys. Res. Commun. 21, 242 (1965) 24, 427 (1966) K. Morihara, H. Tsuzuki, Biochim. Biophys. Acta 118, 215 (1966). Stability studies Y. Ohta, J. Biol. Chem. 242, 509 (1967). Inhibition studies H. Matsubara et al., Biochem. Biophys. Res. Commun. 34, 719 (1969) J. Murphy et al., Arch. Biochem. Biophys. 202, 405 (1980). Purification H. Matsubara,... 

Currently, five kinds of nanocellulose are known CNP, ANP, NFC, BNC, and CNY. These nanocellulose types have unique features, such as small dimensions, a variety of shapes and enhanced specific surface, high sorption and absorption ability, high thermal stability, and high resistance to dilute solutions of acids and alkalis, organic solvents, proteolytic enzymes, antioxidants, and some other TAS. The specific features open new, promising application areas, particularly in various branches of care and cure, such as hygiene, cosmetics, pharmaceutics, medicine, etc. 

A comparative study of the isolated CHMO enzyme with that overexpressed in E. coli has shown that they are practically identical. The slight difference in pH and thermal stability was due to the differences in trace impurities with proteolytic enzymes present in the E. coli host [81]. At present, the main focus has been on using intact cells expressing CHMO as a biocatalyst. Intact cells of designer bioreagents are more accessible and more chemical friendly than the isolated enzymes used for biotransformations. 

Conjugates between polysaccharides (e.g. dextrans, starch, and dextrin) and proteins (e.g. lysozyme, chymotrypsin, j8-glucosidase, casein, and serum albumin) have been prepared with the aid of cyanogen bromide. Loss of enzymic activity was offset by increases in the thermal stability and the resistance to proteolytic digestion. Glutaminase-asparaginase from Acinetobacter has been... 

Ovomucoid and ovomucin are the proteins responsible for the viscosity and gel-like consistency of egg white. Ovomucoid (28 kDa, p7=4.4-4.6) is composed of three components which differ in carbohydrate composition on the JV-terminus of the molecule. Ovomucoid inhibits trypsin and other proteolytic enzymes and is a strong allergen. The stability to thermal denaturation (in an acidic medium) is associated with nine disulfide bonds in the molecule. 

Viral sialidases are membrane components, and as such show greater thermal stability relative to bacterial enzymes. They require purification after release from the virus. Complexes in the range of 1-2 x 105 daltons, or monomers in the range of 5-6 X 104 daltons have been reported for sialidase preparations without proteolytic degradation (see Drzeniek 1972, Rosenberg and Schengrund 1976). 

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