Measurements have been performed of the excited-state lifetimes and fluorescence yields of papain tryptophan units when acyl derivatives of Phe-glycinal are bound at the active site of the enzyme. The enhancement of tryptophan fluorescence in complexes of papain with the acetyl or benzyloxycarbonyl derivatives is not stereospecific with respect to the configuration of the phenylalanyl residue, ...

It is now generally agreed that papain possesses a single reactive sulfhydryl group which is essential for activity and which probably participates in the catalytic mechanism by forming acyl intermediates with the different substrates (2, 3). Smith (4) has claimed that the essential sulfhydryl group of papain is kinetically more active than most protein sulfhydryl groups and that it possesses d...

In rabbits, the depletion of cartilage matrix which occurs following intravenous administration of papain treated with iodacetamide is attributable to a portion of the enzyme in the disulfide form which has not undergone alkylation. It is this portion that is reactivated in cartilage in vivo and initiates the enzymatic breakdown of the protein-polysaccharide complex which forms a major componen...

The protein crystals found in potato (Solanum tuberosum 1.) tuber cells consist of a single 85-kD polypeptide. This polypeptide i s an inhibitor of papain and other cysteine proteinases and i s capable of binding several proteinase molecules simultaneously (P. Rodis, J.E. Hoff [1984] Plant Physiol 7 4 907-911). We have characterized this unusual inhibitor in more detail. Titrations of papain ac...

The activation of papain with four different activators is not accompanied by the binding of any of them to the protein. These experiments, taken together with previously reported results, show that the inactive form of papain prepared by the method of Kimmel and Smith (J. Biol. Chem., 207, 5’75 (1954)) is a mixed disulfide formed between the active site sulfhydryl group of the protein and free...

Papain activity was studied in water-organic solvent mixtures using the fluorogenic substrate Dabcyl-Lys-Phe-Gly-Gly-Ala-Ala-Edans. The increase of organic solvent (MeOH, EtOH, iPrOH, TFE, MeCN, (MeO)2Et and DMF) concentration in the mixture caused a substantial decrease the initial rate of papain-catalyzed hydrolysis. Moreover, the number of papain active sites decreased with the increase of D...

The protein crystals found in potato (Solanum tuberosum L.) tuber cells consist of a single 85-kD polypeptide. This polypeptide is an inhibitor of papain and other cysteine proteinases and is capable of binding several proteinase molecules simultaneously (P. Rodis, J.E. Hoff [1984] Plant Physiol 74: 907-911). We have characterized this unusual inhibitor in more detail. Titrations of papain acti...

Latex from Carica papaya is rich in bioactive compounds, especially papain, which may help to control parasitic diseases. This study evaluated the efficacy of latex from C. papaya and purified papain against Strongyloides venezuelensis. The Egg Hatching Test (EHT) and the Larval Motility Test (LMT) using fresh and frozen latex (250mg/mL), lyophilized latex (34mg/mL), and purified papain (2.8 mg...

The purpose of the present study was to evaluate the role of exercise training on the development of papain-induced emphysema in rats. Our hypothesis was that the increase in pulmonary tissue stretching associated with exercise could increase the severity of a protease-induced emphysema. Wistar rats were randomly assigned to four groups (n = 10 for each group) that received, respectively, intra...

The cleavage into large fragments of both normal and immune rabbit y-globulin by cysteine-activated papain was reported by Porter (1, 2). In the case of immune y-globulin the antibody activity was found associated with two of the three principal fragments isolated. Nisonoff et al. (3) have carried out the cleavage of rabbit immune y-globulin into similar fragments with a sedimentation constant ...