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C M Collins

Publications and source records attributed to C M Collins.

At least 91 records · Page 5Linked to original sources
PubMed1985

A monoclonal antibody that detects HLA-D region antigen in routinely fixed, wax embedded sections of normal and neoplastic lymphoid tissues.

We describe the use of a monoclonal antibody (TAL-IB5) to HLA-D region alpha-chains that reacts well with HLA-D positive cells in normal and neoplastic lymphoid tissues fixed in routine fixatives and embedded in paraffin wax in the conventional fashion. This antibody should prove to be useful in routine histological investigations of lymphoid and possibly other neoplasms as well as other non-neoplastic conditions where the immune system plays an important part.

Antibodies, Monoclonal↗
PubMed1984

Interaction of diphtheria toxin with adenylyl-(3',5')-uridine 3'-monophosphate. I. Equilibrium and kinetic measurements.

Purified diphtheria toxin from various sources contains tightly, but noncovalently, bound nucleotides, the major component of which is adenylyl-(3',5')-uridine 3'-monophosphate (ApUp). We used ApUp radiolabeled with 32P to measure equilibrium dissociation constants (KD), and association and dissociation rate constants (k+1 and k-1, respectively) under various conditions. Diphtheria toxin bound 1 molar equivalent of ApUp, regardless of the temperature. Values of KD were 0.2 nM (25 degrees C) and 1.8 nM (37 degrees C) as determined by flow dialysis. No difference in KD was observed between the nicked and intact forms of toxin. The dissociation rate constant showed marked variation with temperature, ranging from 1.8 X 10(-4) s-1 at 5.5 degrees C (t 1/2 of the complex = 64 min) to 2.5 X 10(-2) s-1 at 25 degrees C (t 1/2 of the complex = 28 s). By contrast, k+1 varied only by a factor of 5 over the same temperature range (2.0 X 10(7) M-1 s-1 at 5.5 degrees C; 9.6 X 10(7) M-1 s-1 at 25 degrees C). The KD at 5.5 degrees C, calculated from the ratio of k-1/k+1, is 9 pM, which represents the strongest affinity of a dinucleotide for a protein ever reported. Affinity was maximal in the range of pH 6.5 to 7.1 and was sensitive to ionic strength. Thermodynamic parameters of the system were calculated.

Chemical Phenomena↗
PubMed1984

Interaction of diphtheria toxin with adenylyl-(3',5')-uridine 3'-monophosphate. II. The NAD-binding site and determinants of dinucleotide affinity.

Diphtheria toxin (DT) binds NAD with a KD of about 10 microM and adenylyl-(3',5')-uridine 3'-monophosphate (ApUp) with KD values ranging from 9 pM to 1.8 nM, depending on temperature (Collins, C. M., Barbieri, J. T., and Collier, R. J. (1984) J. Biol. Chem. 259, 15154-15158). Here we report experiments to explore relationships between ApUp binding and NAD binding to DT and to identify structural features of ApUp that determine its high affinity for DT. NAD, adenine, and nicotinamide competitively inhibited ApUp binding to DT, and we confirmed that ApUp blocked the binding and hydrolysis of NAD. Binding of P-site ligands to the toxin blocked interactions with ApUp. CRM197, a mutant form of DT defective in NAD binding and hydrolysis, bound ApUp 5,000-fold less tightly than did DT. These results are consistent with models in which the ApUp- and NAD-binding sites on DT overlap or are identical. Various mono-, di-, and oligonucleotides were studied as competitors of ApUp binding or the NAD-glycohydrolase reaction. The results imply that the high affinity of ApUp for DT depends on the presence of the 3'-terminal phosphate and a 3'-5' internucleoside linkage. There was strong specificity for adenine as the 5' base, but only weak specificity for uracil as the 3' base. Oligoribonucleotides containing additional nucleotides at either or both ends of ApUp sequences bound to the toxin 1-3 orders of magnitude less avidly than ApUp. Oligodeoxyribonucleotides containing dApdT sequences bound with still lower affinities. In contrast to the case with whole toxin, ApUp bound to fragment A less avidly than did NAD, and elimination of the 3'-terminal phosphate of ApUp resulted in increased affinity for the protein. These differences may reflect the absence in free fragment A of interactions with the cationic P-site, located on the toxin's B moiety.

Chemical Phenomena↗
PubMed1980

Changing times.

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Attitude↗