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H P Jones

Publications and source records attributed to H P Jones.

5 recordsLinked to original sources
PubMed1979

Isolation and characterization of Ca2+-dependent modulator protein from the marine invertebrate Renilla reniformis.

An acidic, low molecular weight (18 400--19 100) protein capable of activating porcine brain phosphodiesterase in the presence of calcium has been purified 2700-fold from the anthozoan coelenterate, Renilla reniformis. The protein has physical, spectral, and chemical properties similar to those of modulator proteins isolated from mammalian species. Amino acid composition studies reveal no significant differences between the Renilla and mammalian modulator proteins. For example, we observed 1 mol of epsilon-N-trimethyllysine per mol of protein, no tryptophan or cysteine, and high levels of glutamic and aspartic acid residues. The protein from Renilla complexes with troponin I and T subunits in the presence of calcium and quantitatively replaces porcine brain modulator in the calcium-dependent activation of porcine brain phosphodiesterase. The protein has a high affinity for calcium as judged by the low levels of free calcium required for modulator-dependent activation of phosphodiesterase. The similarities in physical and chemical properties, high affinity for calcium, and identical calcium-dependent activities of this protein from Renilla (as compared with modulator protein purified from mammalian systems) suggest that a high degree of structural conservation has been retained in modulator proteins isolated from these diverse evolutionary forms.

Amino Acids↗
PubMed1977

In vitro reconstitution of demolybdosulfite oxidase by molybdate.

Reconstitution of purified demolybdosulfite oxidase from rat liver has been achieved using inorganic molybdate as the source of molybdenum. The activation process has a pH optimum of 7.4 and is dependent on concentrations of molybdate and demolybdoenzyme. The reaction is inhibited by high concentrations of anions and by reduction of the demolybdoenzyme and requires incubation temperatures higher than 30 degrees. A reconstitution mechanism involving loss of tungsten and concomitant replacement with molybdenum in those demolybdo molecules which contain tungsten is supported by the following observations: (a) the extent of activation achieved by molybdate corresponds to the proportion of molecules in the preparation which contain tungsten. (b) Incubation of the demolybdoenzyme preparation at 37 degrees in the absence of molybdate results in progressive and concentration-dependent loss of ability to be reconstituted by molybdate and a corresponding but more rapid loss of tungsten from the enzyme. The reconstituted enzyme displays the molybdenum EPR signal characteristic of native enzyme and is inactivated by incubation at 42 degrees in a manner identical to native sulfite oxidase.

Animals↗
PubMed1976

Long-term immunoglobulin G production by transplanted thymus cells.

Two sublines of CBA/H mice congenic for the Igl allotype locus were used to study donor-allotype IgG2a concentrations in the serum of mice injected intravenously with thymus cells. High concentrations (up to several mg/ml) were found in x-irradiated recipients (exposed to 650 rad, or to 900 rad with a restorative injection of fetal liver cells). The highest concentrations were seen 1-2 months after injection, but detectable quantities were still present in most individuals after 377 days. No donor-allotype Ig was detected in non-irradiated recipients. Cell for cell, lymph node cells were about as efficient as thymus cells at transferring IgG production. Although pluripotent hematopoietic stem cells were found in the thymus, their concentration (about 10(-8)) was too low to account for the results. It is suggested that the thymus contains B lymphocytes, or their precursors, with considerably greater powers of self-maintenance and expansion than are possessed, on average, by the B lymphocytes in lymph nodes.

Animals↗