Biomedical subjects

H Manuel

Publications and source records attributed to H Manuel.

3 recordsLinked to original sources

PubMed1984

The platelet reticular network.

Human platelets have been observed by scanning electron microscopy after spreading on glass substrates followed by brief incubation in 1 mM ZnCl2 and subsequent shearing with a jet of buffer. The surfaces of many cells in such preparations are noted to consist of a reticular meshwork similar in appearance to the membrane skeleton of erythrocytes. In some preparations the reticular network is partially or almost entirely disrupted revealing an internal trabecular cytoskeleton and in the central region of the spread cell, granules associated with the cytoskeletal matrix. These results confirm previous observations obtained in TEM and HVEM studies of platelets and in addition provide information concerning the relative disposition of the filament systems in such spread cells. Preliminary results from sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of platelets and isolated platelet membranes suggest a basis for the effect of ZnCl2 on various platelet cytoskeletal and membrane components.

Blood Platelets↗

PubMed1980

Effect of divalent cations on the proteolysis of vertebrate and invertebrate muscle myosin.

Analysis by SDS-polyacrylamide gel electrophoresis of the products of alpha-chymotryptic digestion of lobster abdominal muscle myosin has shown that the presence or absence of Ca2+ during proteolysis does not have a major influence on the site of cleavage of the parent molecule, as it does for proteolysis of vertebrate muscle myosin. By following H+ liberation on the pH-stat during proteolysis, it has been found that the divalent cation only suppresses digestion of lobster myosin by about 15% as compared with proteolysis in the absence of Ca2+. Additionally, the subfragment-1-like species made by alpha-chymotryptic digestion of lobster myosin at low ionic strength is much more susceptible to degradation by trypsin than is vertebrate muscle myosin sub-fragment-1, in accordance with the relative susceptibilities of the parent molecules to similar degradation.

Animals↗

PubMed1980

Comparative studies on the structure and aggregative properties of the myosin molecule. II. THe substructure of the lobster myosin molecule.

Previous results (Siemankowski, R.F. and Zobel, C.R. (1976) J. Mechanochem. Cell Motility 3, 171--184) demonstrated that, relative to myosin from rabbit skeletal muscle, myosin from lobster abdominal muscle has four times as many sites susceptible to tryptic fragmentation at the fast rate. The present studies show that limited tryptic digestion of lobster myosin results in the rapid production of three species of rod fragments, all of which are insoluble at low ionic strength; a subfragment-1-like species; and, in addition, the release of large amounts of small peptides (35%, w/w). From estimates of the yields of the tryptic fragments, it is found that although 1 mol equiv. of rod-fragment is produced per mol of myosin digested, only 1 mol equiv. of a subfragment-1-like species is found, suggesting that the lobster myosin subfragment-1-moiety is much more trypsin-labile than the analogous region of rabbit myosin. By two-dimensional electrophoretic analysis, it was found that two of the rod species comprise a large number of unique peptides, collectively, after denaturation in 9 M urea. Similar analysis demonstrates that the subfragment-1-like species contains a small (Mr 25 000), very basic peptide, and that during digestion with trypsin the larger light chain (Mr 20 000) is converted entirely into a more acidic light chain fragment (Mr 18 500). The smaller light chain (Mr 16 000) is resistant to tryptic proteolysis.

Ammonium Sulfate↗