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R Chacko

Publications and source records attributed to R Chacko.

11 recordsLinked to original sources
PubMed1999

Active site characterization of RNase Rs from Rhizopus stolonifer: involvement of histidine and lysine in catalysis and carboxylate in substrate binding.

Chemical modification studies on purified RNase Rs revealed the involvement of a single histidine, lysine and carboxylate residue in the catalytic activity of the enzyme. RNA could not protect the enzyme against DEP- and TNBS-mediated inactivation whereas, substrate protection was observed in case of EDAC-mediated inactivation of the enzyme. K(m) and k(cat) values of the partially inactivated enzyme samples suggested that while histidine and lysine are involved in catalysis, carboxylate is involved in substrate binding. Active site nature of RNase Rs suggests that the inability of the enzyme to readily convert 2',3'-cyclic nucleotides to 3'-mononucleotides is probably due to the absence of catalytically active second histidine residue.

Binding Sites↗
PubMed1998

Extracellular ribonuclease from Rhizopus stolonifer: characteristics of an atypical--guanylic acid preferential--enzyme from ribonuclease T2 family.

An extracellular ribonuclease from Rhizopus stolonifer (designated as RNase Rs) was purified to homogeneity by chromatography on DEAE-cellulose followed by CM-cellulose. The Mr of the purified enzyme determined by gel filtration and SDS-PAGE is 25,000 and 28,200, respectively. RNase Rs is a glycoprotein and contains 10.5% neutral sugar. It is an acidic protein with a pI of 5.0 and has a blocked N-terminus. The optimum pH and temperature are 5.5 and 45 degrees C, respectively. RNase Rs shows high stability between pH 6.0-10.0. Divalent cations like Zn2+, Hg2+ and Cu2+ inhibit the enzyme activity whereas, mononucleotides does not have any significant effect. The enzyme cleaves RNA to 3'-mononucleotides via 2',3'-cyclic nucleotides, with preferential liberation of 2',3'-cyclic GMP, suggesting that RNase Rs is a guanylic acid preferential cyclizing RNase. Moreover, cyclic nucleotides generated are highly resistant to further hydrolysis.

Cations, Divalent↗
PubMed1983

The classification of paranoid disorders in the elderly: a clinical problem.

Data on the incidence of Paranoid Disorders according to modified DSM-III criteria in an outpatient geriatric clinic are presented. Results are consistent with previous research data which find paranoid symptomatology to be common in elderly psychiatric patients. The current definition of paranoid disorders is too narrow to encompass those elderly with good premorbid adjustment whose later life paranoid disorders often include hallucinations. The DSM-III paranoid subtype system does not have a separate category for chronic paranoid symptomatology which, although commonly seen in the old, is now subsumed under an atypical paranoid disorder classification. Further research into late life psychopathology may provide refinement of other diagnostic categories and a better understanding of the developmental relationship between personality disorder and major psychopathology.

Aged↗
PubMed1980

Cerebral lateralization: relation to subject's sex.

Patterns of reflective LEM's have been correlated to a number of cognitive and personality variables, bu the relationship to sex, education, and mental illness is unclear. In this study females produced significantly more R-LEM overall indicating a preferential use of left hemisphere mechanisms when they initiate reflective thought. Females also produced more R-LEM for verbal nonemotional material, suggesting stronger lateralization of language abilities to their left hemisphere. Emotional and spatial stimuli were less well lateralized to the right hemisphere in females, and education was an unimportant variable for both sexes. Schizophrenia was independently associated with increases in total R-LEM indicating increased left hemisphere activity in this group.

Educational Status↗