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Biomedical subjects

M W Pandit

Publications and source records attributed to M W Pandit.

At least 37 records · Page 2Linked to original sources
PubMed1988

Prediction of the recognition sites on 16S and 23S rRNAs from E. coli for the formation of 16S-23S rRNA complex.

Interactions between RNA molecules have been postulated to play an important role in the assembly of ribosomes. Using the sequence analysis and the search of continuous complementary regions on 16S rRNA and 23S rRNA, the recognition sites involved in the formation of ribosome of E. coli are postulated. The number of postulated sites was narrowed down by taking available experimental data. The suggestive evidence for correct postulation is obtained from sequence comparison studies of 16S and 23S rRNAs from various species. The sites 891-899 and 1195-1203 on 16S rRNA along with the corresponding complementary sites 1904-1912 and 760-768 on 23S rRNA are predicted to be the most probable candidates for the sites of recognition between 16S and 23S rRNAs. The possibility of the involvement of the additional site 630-638 on 16S rRNA with its complementary site 2031-2039 on 23S rRNA cannot be ruled out.

Computer Simulation↗
PubMed1987

A new ribonuclease from cobra venom (Naja naja) showing specificity towards cytidylic acid.

A ribonuclease was isolated and purified to homogeneity from cobra venom. The enzyme was found to be homogeneous on SDS and non-SDS polyacrylamide gel electrophoreses, and high performance liquid chromatography. The purified enzyme hydrolysed poly(rC), but not poly(rA), poly(rU), poly(rG), poly(rI), or poly(rI).poly(rC). The presence of magnesium was found to be an essential requirement for the nucleolytic activity of this enzyme.

Animals↗
PubMed1987

Buoyant density and molecular weight calculations on an Apple II microcomputer from equilibrium banding experiment on analytical ultracentrifuge.

Buoyant density is one of the non-destructive measurements of viruses, nucleic acids etc. which help in characterizing these entities in terms of their chemical composition and physical conformation. In recent years equilibrium sedimentation in CsCl buoyant density gradient has been proved to be a powerful tool for genome characterization. The method enables one to obtain information such as the absolute and the relative buoyant density of the material and its molecular weight. This communication describes a program in BASIC which calculates these parameters from the raw data obtained directly from the experiment. The program is fully interactive, user-oriented, and written keeping in view biologists and biochemists as the main users. The program has a built-in option to calculate either the absolute or the relative buoyant density and the molecular weight.

Algorithms↗
PubMed1986

Helix-destabilization of deoxyribonucleic acid and poly[d(A-T).d(A-T)] by bovine seminal ribonuclease.

A ribonuclease isolated earlier from bovine seminal plasma by DNA-affinity chromatography (Ramakrishnamurti, T. and Pandit, M.W. (1983) J. Chromatogr. 260, 216-222) has now been shown by thermal denaturation studies to destabilize the double-helical structure of DNA and poly[d(A-T).d(A-T)]. Thermal denaturation profiles of DNA in the presence of the protein are much more complicated due to the denaturation of protein itself in the temperature range over which DNA predominantly melts. The protein shows relatively stronger affinity towards denatured DNA as compared to native DNA. The action of micrococcal nuclease on DNA and its complexes with ribonuclease A and bovine seminal ribonuclease indicates that both of these proteins destabilize the double-helical structure of native DNA and thereby render the DNA more sensitive to the micrococcal nuclease.

Animals↗
PubMed1986

Analysis of repeating oligonucleotide sequences in ribonucleic acids using an Apple II microcomputer.

A simple computer program has been developed to locate repeating subsequences of all possible lengths in a given nucleic acid. The observed number of repeats of subsequences was compared with the expected number of such repeats in several RNAs. The analysis showed that, in the case of rRNAs, there are no constraints in the choice of the fourth and the higher order nucleotides, while the selection is maximum at the level of nearest neighbour. This is, however, not true for RNAs coding for proteins, where the constraints are also found at the level of nucleotides containing five or more bases.

Algorithms↗
PubMed1985

Prediction of strong antigenic determinant of seminalplasmin and ribonuclease from the amino acid sequence.

It has been reported earlier [Hopp, T.P. & Woods, K.R. (1981) Proc. Natl. Acad. Sci. US 78, 3824-3828] that the antigenic determinants of a protein can be delineated by examining the average local hydrophilicity values along the peptide chain. I have used this method to predict the strong antigenic determinants of two proteins, seminalplasmin and ribonuclease, of known sequence. In the former case, the N-terminal segment 1-14, and in the latter case the segments 27-38 and 80-86, are predicted to possess the antigenic determinants of the two proteins. Experimental verification already exists for the former case.

Amino Acid Sequence↗
PubMed1984

Computation of the sedimentation coefficient, S0(20),w, from the analytical ultracentrifuge run by an interactive program on the Apple II microcomputer.

We have developed a computer program for the calculation of the sedimentation coefficient of a macromolecule from the raw data collected from an analytical ultracentrifuge run. The program is written for the Apple II microcomputer and is capable of calculating the sedimentation coefficient at an infinite dilution from the data collected at varying concentrations.

Computers↗
PubMed1984

Identity of the ribonuclease from bovine seminal plasma with ribonuclease BS-1, and its sensitivity to polyvinyl sulphate.

A ribonuclease (RNAase BSD) isolated by us earlier from bovine seminal plasma by DNA-affinity chromatography is shown to be homogeneous on polyacrylamide gel electrophoresis, analytical ultracentrifuge and high performance liquid chromatography. From amino acid analysis, high performance liquid chromatography and enzymatic and physicochemical studies, this enzyme is shown to be identical to RNAase BS-1 reported by D'Alessio et al. ((1972) Eur. J. Biochem. 26, 153-161). Immunological studies support this observation. It has also been shown that, as compared to RNAase A, this enzyme is more sensitive to polyvinyl sulphate inhibition.

Amino Acids↗
PubMed1983

Studies on the size and shape of rabbit intestinal glucoamylase-maltase complex.

Rabbit intestinal glucoamylase-maltase was examined in detail with respect to its molecular weight, sedimentation, diffusion and viscosity. It is a large asymmetrical molecule, with a molecular weight of 750 000-760 000. Its appearance under the electron microscope supports the idea that it is a long string (62.0 nm) consisting of eight beads of diameter 6.0 nm each and a surface-to-surface interbead distance of approx. 2.0 nm. The shape of the enzyme derived from its hydrodynamic behaviour by using the string-of-spherical-beads model originally proposed by Kuhn [(1932) Z. Phys. Chem. Abt. A 161, 1-32] and later modified by Shulman [(1953) J. Am. Chem. Soc. 75, 5846-5852] fits moderately well with the electron-microscopic picture. The beads might represent about six subunits, and the absence of sulphur from the enzyme and the inability to dissociate the enzyme by conventional methods indicate the possibility of unusual covalent cross-linking between the subunits and between the beads.

Animals↗
PubMed1983

Denaturation studies on bovine pancreatic ribonuclease. Effect of trichloroacetic acid.

Exposure of ribonuclease (EC 3.1.27.5) to 5% trichloroacetic acid solution is found to partially inactivate the enzyme. This inactivation is a function of time of exposure to trichloroacetic acid and reaches a plateau of about 45% residual activity. Higher concentrations of trichloroacetic acid lead to greater inactivation. Physicochemical properties such as sedimentation coefficient, gel-filtration behaviour and polyacrylamide gel electrophoresis of the trichloroacetic acid-treated enzyme remain unaffected as compared to the untreated enzyme. However, spectrophotometric titration of the trichloroacetic acid-treated enzyme revealed that one of the three 'buried' groups of tyrosine is exposed to the outside surface of the molecule. Near ultraviolet CD spectra supported these observations. Far ultraviolet CD spectra suggested some refolding of the enzyme after trichloroacetic acid treatment. Immunological determinants on the molecule remain unaltered upon trichloroacetic acid treatment. It is concluded that the exposed tyrosine group may be causing a conformational change in the protein and this change may be indirectly responsible for the observed reduction in the activity after trichloroacetic acid treatment.

Animals↗