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J M Kehoe

Publications and source records attributed to J M Kehoe.

At least 19 recordsLinked to original sources
PubMed1987

Mouse alpha-macroglobulin. Structure, function and a molecular model.

Mouse alpha-macroglobulin (M-AMG) is believed to be a functional homologue of human alpha 2-macroglobulin (h-alpha 2M). The subunit composition, the tryptic cleavage pattern before and after methylamine incorporation and the two-dimensional tryptic-peptide mapping, however, indicate that these two proteins are structurally distinct. M-AMG is composed of two major types of polypeptides (Mr 163,000 and 35,000) together with a minor polypeptide (Mr 185,000), whereas h-alpha 2M has only one type of polypeptide (Mr 185,000). After incorporation of methylamine, there is no change in the normal tryptic-cleavage pattern of M-AMG; however, tryptic cleavage of h-alpha 2M is severely retarded [Hudson & Koo (1982) Biochim. Biophys. Acta 704, 290-303]. The N-terminal sequence of the 163,000-Mr polypeptide of M-AMG shows sequence homology with the N-terminal sequence of h-alpha 2M. The amino acid compositions of M-AMG and its two major polypeptide chains are compared. Thermal fragmentation studies show that the 163,000-Mr polypeptide is broken down into 125,000-Mr and 29,000-Mr fragments. Trypsin-binding studies show that M-AMG can bind two molecules of trypsin/molecule. Inactivations of the trypsin-binding property of M-AMG and h-alpha 2M with methylamine show similar kinetics of inhibition at 4 degrees C. A structural model of M-AMG is proposed, based on accumulated data.

Amino Acids↗
PubMed1987

Characterization of a homogeneous paraprotein from a horse with spontaneous multiple myeloma syndrome.

A novel myeloma paraprotein has been isolated from a horse with a lymphoid tumor. The protein was a euglobulin and consequently was readily isolated from serum in pure form and high yield by simple dilution in distilled water. The purified intact protein had a molecular weight of 150,000 and was composed of heavy and light chains, both of which had blocked amino-termini and were thus not susceptible to amino-terminal sequence analysis. The amino acid compositions of these respective chains corresponded to those of comparable chains from immunoglobulins of other species. Peptide maps of paraprotein light chains prepared by high pressure liquid chromatography corresponded in part to those of normal pooled equine light chains. The identification of this paraprotein as an equine AI (aggregating immunoglobulin) protein was confirmed by serological analysis using a specific antiserum. The relationship of this particular protein to other members of the immunoglobulin family was further demonstrated by the production of an anti-idiotypic antiserum individually specific for this molecule.

Animals↗
PubMed1977

Molecular characterization of limulin, a sialic acid binding lectin from the hemolymph of the horseshoe crab, Limulus polyphemus.

The sialic acid binding lectin, limulin, was isolated by gel filtration and ion-exchange chromatography from the hemolymph of Limulus polyphemus. When the purified protein was characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence of beta-mercaptoethanol, two major protein bands were observed. These two bands, subsequently found to contain carbohydrate as well, corresponded to molecular weights of 25 000 and 27 000. Amino acid sequence analyses were performed on both the intact protein and isolated cyanogen bromide fragments. The following primary structural features were noted in the amino-terminal region of limulin: (1) the absence of histidine and alanine from the NH2-terminal 50 residues; (2) the presence of five of the total eight prolines of the molecule between positions 13 and 30; and (3) a possible carbohydrate attachment site consisting of only the amino acids proline and serine between residues 13 and 19. The resultsof cyanogen bromide cleavage studies confirmed the presence of 2 methionine residues per subunit, at positions 25 and 58 respectively. No sequence heterogeneity was observed in this study. While it is quite possible that limulin plays some role in the defense mechanisms of the horseshoe crab, there is no obvious sequence homology between this invertebrate lectin and vertebrate immunoglobulins.

Agglutinins↗
PubMed1976

The amino-terminal sequence of the VHIII subgroup of pooled porcine IgG.

Pig gamma-chains contain a significant fraction of the unblocked VHIII variable region subgroup. The amino terminal sequence (30 residues) was found to be uniform and more than 90% homologous with the prototype sequence of the human VHIII subgroup. An additional VHIII phylogenetically associated residue, glutamic acid in position 2 was identified in these porcine heavy chains.

Amino Acid Sequence↗
PubMed1976

Chromatographic isolation of the hemagglutinin polypeptides from influenza virus vaccine and determination of their amino-terminal sequences.

The influenza virus hemagglutinin polypeptides, HA1 and HA2, have been purified by gel filtration in the presence of sodium dodecyl sulfate from a vaccine preparation of the recombinant strain Heq1N2. Use of this technique for purification of the hemagglutinin polypeptides eliminated the need for proteolytic agents for removal of the hemagglutinin from the virus particles and 100-300 mg of virus yielded 10-30 mg of viral protein per chromatographic cycle. Because proteolysis is not required to remove the spikes from the viral envelope, the envelope-embedded HA2 polypeptide was purified in its entirety for structural analysis. Amino-terminal sequence analysis of the smaller polypeptide, HA2, revealed a cyclic repetition of glycyl residues through the first 24 residues at every third to fourth position. The sequence through the first 10 residues was identical to that presented by Skehel and Waterfield for other type A influenza viruses [(1975) Proc. Nat. Acad. Sci. USA 72, 93-97]. The HA1 (Heq/) polypeptide, on the other hand, had different amino acids at three or four out of the first 10 residues of the amino-terminal sequence when compared to HA1 from H0, H1, or H2 subtypes (Skehel and Waterfield). The present study has demonstrated the feasibility of the use of vaccine virus as a source of large quantities of viral protein for determination of primary structure.

Amino Acid Sequence↗
PubMed1975

The amino acid sequence of ragweed pollen allergen Ra5.

The complete amino acid sequence of Ra5, a ragweed pollen allergen, has been determined. Allergen Ra5 is a low molecular weight protein of 45 residues derived from Ambrosia elatior, the short ragweed. It contains no detectable carbohydrate or lipid and has four disulfide bridges. The total structure was determined on 1.4 mumol of material and indicates that structural analysis is increasingly possible on relatively small amounts of highly purified material when a combination of automated and manual sequencing techniques and highly sensitive detection systems is employed. This represents the first complete amino acid sequence of a ragweed allergen and it should provide a basis for many structure-function correlative experiments in the field of immediate hypersensitivity.

Alkylation↗
PubMed1975

Transplantable immunoglobulin-secreting tumors in rats. VI. N-terminal sequence variability in LOU/C/Wsl rat monoclonal heavy chains.

Most of the spontaneous ileocecal immunocytomas of LOU/C/Wsl strain rats secrete large amounts of monoclonal immunoglobulins. Amino acid sequence studies were undertaken on the heavy chains of 13 of these proteins and on pooled heavy chains from LOU rats to define the structural variability in the amino terminal region of the rat heavy chain. Characteristic VHIII sequences were found in both the myeloma proteins and the heavy chains from the pool. The data confirm previous conclusions concerning the rat VHIII subgroup that had been derived from studies of pooled heavy chains from Sprague-Dawley rats. In particular phylogenetically associated residues, identical to those previously determined in the Sprague-Dawley pool, were found in the LOU/C/Wsl rat myeloma proteins. There were two unexpected findings: 1) hypervariability at position 16 of the rat VHIII myelomas as contrasted with more than 90% glycine in the pool, and 2) a striking homology of one rat myeloma heavy chain with the variable region of the MOPC 315 mouse alpha-chain. The findings show that the rat myeloma system provides useful proteins for sequence analysis but indicate that some sequence pattern differences can be detected between the myeloma proteins and pooled immunoglobulins from this species.

Amino Acid Sequence↗
PubMed1975

Distribution and association of heavy and light chain variable region subgroups among human IgA immunoglobulins.

A series of randomly selected human IgA myeloma proteins were examined for the presence of the VHIII subgroup as defined by the possession of an unblocked amino terminal amino acid and characteristic linked residues along the heavy chain. Blocked heavy chains were classified as VHB proteins. The data showed that 20 of 30 such random alpha chains (67%) were classifiable as members of the VHIII subgroup. Similarly, 75% of heavy chains isolated from pools of normal serum IgA contained a VHIII variable region. The pattern stands in marked contrast to the situation in human IgG proteins where approximately 20% of heavy chains from both pools and myeloma proteins are VHIII. There was thus a clear divergence of the pattern of variable region: constant region association between these two classes of immunoglobulin. Some more limited data were obtainable for the light chains of the IgA myeloma proteins. Certain predilections for light chain subgroup:heavy chain subgroup (VHIII or VHB) associations were discernable, but more data are required for definite conclusions. Overall, this study suggests that although the pool of available variable region sequences is indeed shared among human IgA and IgG proteins, the partitioning is not exactly equivalent between the two immunoglobulin classes. The pattern is particularly apparent at present for the VHIII subgroup which comprises approximately 70% of human alpha chains and only about 20% of human gamma chains.

Amino Acid Sequence↗
PubMed1974

Structure of antibodies with shared idiotypy: the complete sequence of the heavy chain variable regions of two immunoglobulin M anti-gamma globulins.

The complete amino acid sequence of the heavy chain variable regions of two different molecules of immunoglobulin M anti-gamma globulin has been determined. These proteins, from different human patients, had independently been shown to share idiotypic specificity. Only eight sequence differences were discernible for the entire length of their heavy chain variable regions. Five of the differences occurred outside hypervariable regions, while three were placeable within such regions. A comparison of these molecules of anti-gamma globulin with the seven human V(H)III variable region sequences presently available for immunoglobulins without known antibody activity showed that the great majority of sequence differences between the two idiotypically similar antibodies and these seven proteins were confined to hypervariable regions. This study illustrates in precise terms a convergence of the distinct immunological properties of idiotypy, hypervariable region structure, and combining site specificity as they relate to the variable region of the immunoglobulin molecule. To a great degree these properties now appear to be a reflection of the same structural attributes of the variable region.

Amino Acid Sequence↗