Pepsin hemoglobin

Piper and Fenton [10] indicated that extreme acidity or basicity of the gastric juice denaturalize the enzymatic activity of the pepsin, which shows has a higher activity at a pH = 2. At pH = 5 the enzyme starts to deactivate and at pH= 7, the enzyme irreversibly lose its activity. Fig. 3 shows the pepsin UV-visible spectra before and after interaction with the zeolites while Fig 4 shows the enzymatic activity of the denatured hemoglobin proteolysis versus reaction time. 

Cyt c, myoglobin = hemoglobin, serum albumin, egg albumin, pepsin... 

Anson, M.L. 1938. The estimation of pepsin, trypsin, papain and cathepsin with hemoglobin. J. Gen. Physiol. 22 79-89. 

Schlamowitz, M. and Peterson, L.U. 1959. Studies on the optimum pH for the action of pepsin on native and denatured bovine serum albumin and bovine hemoglobin. J. Biol. Chem. 234 3137-3145. 

The activity of pepsin powder is detenuined by comparing the quantity of peptides nonpredpitable by trichloroacetic add solution R and assayed using the phosphomolybdotungstic reagent R which ate released per minute from a substrate of hemoglobin solution R with the quantity of such peptides released by pepsin powder BRP from the same substrate in the same conditions. 

Figure 1. Optimum pH of pepsin partially purified from the stomach lining of arctic cod 30°C ( ) 5°C (A) A 280 = absorbancy of TCA solubles at 280 nm. Pepsin was assayed with acid-denatured hemoglobin (2%) at the indicated temperatures and activity was monitored by measurements of TCA-solu-ble products (53).

Figure 5. Arrhenius plot for arctic cod pepsin hydrolysis of hemoglobin...

Figure 6. Arrhenius plot for Greenland cod pepsin-catalyzed hydrolysis of hemoglobin at pH 1.9 (53).

Table V. Apparent Michaelis Constants for Hemoglobin and Pepsin Isolated from Various Sources...

Figure 13. Substrate velocity curve influence of hemoglobin concentration on its rate of hydrolysis catalyzed by Greenland cod pepsin at 37°C (M), 17°C (A), and 5°C ( ).

Figure 16. Apparent Michaelis constant for hemoglobin and American smelt pepsin at different assay temperatures Lake Melville (WL) Gambo...

After some days in trifluoroacetic acid solution at 5°, the spectra of pepsin and bovine hemoglobin (not shown) exhibit a much more prominent peak in the methionine methyl position. This effect is probably the result of additional rotational freedom, brought about by cleavage of some of the peptide bonds. 

Fig, 23. Quantitation of pepsin by paper electrophoresis and hemoglobin digestion in 165 lyophilized gastric juices of humans. From Class (C3). 

If, as is shown in Table VII, these phosphorus-free proteins are then assayed for proteolytic activity, no loss is found when tested either with hemoglobin (4) or with the synthetic dipeptide, acetyl-L-phenylalanyl di-iodotjTosine (7) as a substrate. This indicates that the phosphorus in these proteins is unessential both for the enzymatic activity of pepsin and for the activation of the precursor, pepsinogen. 

It has long been known that many proteins are extremely sensitive to even dilute acids (e.g., hemoglobin) and bases (e.g., pepsin). Preparative... 

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