A two-step procedure for purification of papain from extract of papaya latex

A method is presented for purifying papain from extracts of papaya latex. The procedure involves precipitation of the extract of papaya latex with sodium chloride followed by affinity chromatography of the redissolved precipitate. Precipitation of the protein from the latex extract is necessary to separate the papain from material which interferes with the binding of papain to the affinity column. During affinity chromatography, the affinity column is overloaded to insure absence in the final product of impurities which are capable of binding to the affinity column.The papain prepared by this procedure yielded an amino acid analysis and an N-terminal amino acid analysis expected for a sample of pure papain. No Met was detected on amino acid analysis nor was the presence of N-terminal residues other than He detected. On polyacrylamide disc gel electrophoresis at pH 4.3, papain prepared by the method described in this work was indistinguishable from crystalline papain which was prepared by the method of Kimmel and Smith, and further purified by affinity chromatography. Both disc gel patterns consisted of a single band and a trailing shadow which was less than 5% of the main band. In routine spectrophotometric assays, the specific activity toward N,α-benzoyl-l-arginine ethyl ester of papain prepared by the procedure described in this work was indistinguishable from crystalline papain prepared by the method of Kimmel and Smith, and further purified by affinity chromatography. Values of 24 sec^?1' and 15 mm were obtained from the turnover number and K_m for the papain-catalyzed hydrolysis of N,α-benzoyl-l-arginine ethyl ester at 25 °C, pH 6.00, $\text{Γ}\text{2 0.30}$ using a pH stat.     

Binding of N-methyl isatin beta-thiosemicarbazone-copper complexes to proteins and nucleic acids.

N-Methyl isatin beta-thiosemicarbazone-copper complexes interact with nucleic acids and proteins as shown by ultraviolet (UV) and visible spectroscopy and Sephadex exclusion chromatography. The Cu++ ions are most effective; Co++ ions have less albeit significant activity. Chelating agents, such as Tris and histidine, high NaCl concentration, and dimethyl sulfoxide reduce the binding of the drug-metal complex. The binding constant of the drug-copper complex to calf-thymus DNA was calculated to range between 6.9 x 10(4) and 2.7 x 10(5) M-1.     

The cytologist and bacterioses of the vaginal-ectocervical area. Clues, commas and confusion

To evaluate the role of the cytologist in the diagnosis of bacterial vaginosis, the predominant bacterial patterns seen in 157 Papanicolaou-stained cervical smears were assessed and classified as large bacillus, anaerobic or scanty. A large bacillus pattern was found in 73 smears (46%), an anaerobic pattern in 77 (49%) and scanty bacteria in 7 (5%). Comma-shaped (curved) bacilli were found in 34 smears. The prevalence of clue cells in smears with anaerobic patterns was 73%. Gardnerella vaginalis was cultured from 89% of the cases with anaerobic-type smears containing clue cells and from 88% of those with anaerobic-type smears lacking clue cells. Mobiluncus sp. was cultured from 83% of the cases with anaerobic-type smears showing curved bacilli and 14% of those with anaerobic-type smears lacking curved bacilli. Papanicolaou-stained smears were found to be more sensitive and more specific for identifying clue cells than were wet preparations. A positive association was found between a positive KOH "whiff" test and the presence of curved bacilli on the Papanicolaou-stained smear. The clinical significance of these findings is discussed.     

Does Learning or Instinct Shape Habitat Selection?

Habitat selection is an important behavioural process widely studied for its population-level effects. Models of habitat selection are, however, often fit without a mechanistic consideration. Here, we investigated whether patterns in habitat selection result from instinct or learning for a population of grizzly bears (Ursus arctos) in Alberta, Canada. We found that habitat selection and relatedness were positively correlated in female bears during the fall season, with a trend in the spring, but not during any season for males. This suggests that habitat selection is a learned behaviour because males do not participate in parental care: a genetically predetermined behaviour (instinct) would have resulted in habitat selection and relatedness correlations for both sexes. Geographic distance and home range overlap among animals did not alter correlations indicating that dispersal and spatial autocorrelation had little effect on the observed trends. These results suggest that habitat selection in grizzly bears are partly learned from their mothers, which could have implications for the translocation of wildlife to novel environments.