Enzymes in digestion

Cellular functions are the result of chemical reactions photosynthesis, respiration, use of enzymes in digestion to break down complex molecules... 

Oshima, G., Shimabukuro, H., and Nagasawa, K. 1979. Peptide inhibitors of angiotensin I-converting enzyme in digests of gelatin by bacterial collagenase. Biochim. Biophys. Acta 566, 128-137. 

Enzymes have found a few applications as therapeutic agents. Some examples are transfusion of fresh blood or its active components in bleeding disorders, oral administration of digestive enzymes in digestive diseases... 

From a bioavailabihty standpoint, the fact that a significant amount of nicotinic acid is in a bound form has important biological consequences. Poor bioavailabihty stems from the fact that the ester linkage is resistance to digestive enzymes. In the case of com, this condition can be alleviated if com is pretreated with alkah. This food preparation method is frequently practiced in Mexico for the preparation of tortillas. 

In the body, this reaction is reversed by the enzyme sucrase. This occurs in digestion, which makes glucose and fructose available for absorption into the blood. Honey bees also carry an enzyme that can hydrolyze sucrose. Honey consists mostly of a 1 1 mol mixture of glucose and fructose with a small amount of unreacted sucrose. 

DIGESTIVE ENZYMES. When digestive enzymes are given in capsule or enteric-coated tablet form, the nurse... 

Major allergens in all vespid venoms are phospholipase A, a 33.5-kDa enzyme which digests cell membranes (Ves vl for V vulgaris) and antigen 5 (Ves v5), a 23-kDa... 

HARA T, MUKUNOKIY, TSUKAMOTO I, MiYOSHi M, HASEGAWA K (1984) Susceptibility of Kintoki bean lectin to digestive enzymes in vitro and its behavior in the digestive organs of mouse in vivo. J Nutr Sci Vitaminol (Tokyo). 30 381-94. 

Reaction of purified Ca " -ATPase with 0.3 mM NBD-Cl in the presence of 1 mM AMP-PNP and 1 mM CaCl2 caused inhibition of ATPase activity with the incorporation of 2= 15 nmol NBD-Cl per mg protein [335]. The inhibition was attributed to the binding of 7-8 nmol NBD-Cl/mg enzyme protein, corresponding to = 1 mol NBD-Cl per mol ATPase. The NBD-labeled enzyme was digested with pepsin and several NBD-labeled peptides were isolated [335]. All peptides contained the Gly-X (Cys) sequence that occurs only in one place in the Ca -ATPase, i.e., at Gly343-Cys344. Therefore NBD-Cl reacts with the same cysteine 344 residue that is also modified by maleimide derivatives [319]. The NBD modified enzyme had only 5-10% of the ATPase activity of the control ATPase, but the steady state concentration of the phosphoenzyme intermediate was only slightly reduced [335]. The Ca ... 

M Yoshioka, RH Erikson, JF Woodly, R Gulb, D Guam, YS Kim. Role of rat intestinal brush-border membrane angiotensin-converting enzyme in dietary protein digestion. Am J Physiol 253 G-781-G-786, 1987. 

Protoplasmic structures are not very stable. Consequently, if protective agents were not employed, destruction of the walls was accompanied by a rapid lysis of the protoplasts, followed by the liberation of most of the cell protein and nucleic acid in soluble form. This could be prevented by employment of the enzyme in a 0.2 M solution of sucrose or cane sugar. After digestion of the cell walls, the living protoplasts rounded up into spheres. 

In paintings, amino acid racemisation depends upon the presence of albuminous binders, such as blood or egg white. The ability to apply this technique is based on the observation that the number of amino acids present in proteins decreases over time. Decay curves are constructed of paint samples of known age. Moreover, amino acid decay rates are also dependant upon micro-organisms (whose enzymes can digest various types of proteins) and environmental conditions [114]. 

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