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Biomedical subjects

C Milstein

Publications and source records attributed to C Milstein.

At least 253 records · Page 14Linked to original sources
PubMed1967

Esters of serine and threonine in hydrolysates of histones and protamines, and attendant errors in amino acid analyses of proteins.

1. Partial acid hydrolysates of histones from various origins and of protamine were analysed by a two-dimensional ionophoretic procedure to reveal strongly acidic ninhydrin-positive components. 2. Histone fractions prepared by extraction with sulphuric acid gave rise to spots identified as serine O-sulphate and threonine O-sulphate. These two compounds, which were not found in hydrolysates of corresponding fractions prepared by extraction with hydrochloric acid, were artifacts. 3. Hydrolysis of proteins in the presence of traces of sulphate can lead to the formation of the O-sulphates of serine and threonine. This can cause errors, which may sometimes be serious, in amino acid analyses of proteins. 4. O-Phosphoserine was obtained in small amounts from some histone fractions and from protamine, but was undetectable in other histone fractions, notably those of lower lysine content.

Activation Analysis↗
PubMed1966

The phosphorylated intermediate in the phosphoglyceromutase reaction.

1. High-voltage paper-electrophoresis methods have been used for the separation of (32)P-labelled phosphoesters. 2. Evidence is presented which indicates that (32)P-labelled phosphopeptides, obtained after acid hydrolysis of phosphoglyceromutase incubated with impure 2,3-di[(32)P]phosphoglycerate, are derived from phosphoglucomutase contamination. 3. The hydrolysis of 2,3-di[(32)P]phosphoglycerate by phosphoglyceromutase has been studied. After an apparent instantaneous hydrolysis of 1 mole of coenzyme/mole of enzyme the reaction proceeds at a very low rate. 4. This hydrolysis seems to be due to the destruction of an enzyme-coenzyme complex. The proportions of the decomposition products of the complex vary according to further handling (pH of ionophoresis). 5. The inorganic [(32)P]phosphate produced by the hydrolysis of the complex and the inorganic [(32)P]phosphate produced by the slow phosphatase activity can be differentiated by the ability of the former to be incorporated into non-radioactive substrate before enzyme denaturation. 6. The effect of enzyme concentration on the stoicheiometry of the slow phosphatase hydrolysis of the diphosphoglycerate is described and this suggests that it may occur via two independent reactions, one of them being the decomposition of the enzyme-coenzyme complex on standing.

Autoradiography↗
PubMed1966

The disulphide bridges of immunoglobulin kappa-chains.

The arrangement of the disulphide bridges of the major component of the light chains of immunoglobulins (kappa-chains) has been studied in the Bence-Jones proteins. Three disulphide bridges have been found. An interchain bridge at the C-terminus has been shown to occur in the dimers of all the proteins studied and was characterized by symmetrical peptides. In the monomer form, the C-terminal half-cystine of the corresponding peptides was linked to a lone half-cystine residue. A second common disulphide-bridge peptide in which a single amino acid difference could be related to the Inv factors of the individual proteins was found in Bence-Jones proteins and in the kappa-chains of normal and abnormal immunoglobulins. Peptides characteristic of a third disulphide bridge studied in three specimens were found to have differences in some residues, but also striking similarities. A methionine peptide has also been characterized in two specimens as a by-product of the technique employed. It is suggested that a general manner of folding may be a common feature of the heterogeneous population of kappa-chains: one bridge which folds an invariable stretch of the chain, another bridge which folds a stretch that varies from protein to protein, and a bridge at the C-terminus which is the interchain link.

Bence Jones Protein↗
PubMed1966

Immunoglobulin kappa-chains. Comparative sequences in selected stretches of Bence-Jones proteins.

Three type K Bence-Jones proteins have been fully reduced and carboxymethylated with high-specific-activity iodo[(14)C]acetate. A tryptic digest and a chymotryptic digest of each protein were fractionated on a Sephadex column and the radioactive peptides were purified by paper electrophoresis. All the proteins studied had five unique carboxymethylated cysteine sequences. Three of these were identical with the exception of a single substitution, and two had some variations. The common peptides could be placed in the C-terminal half of the molecule. The variations around the other two half-cysteine residues provided information about the nature of the variability of the primary sequence of immunoglobulin kappa-chains. The results are consistent with the hypothesis that the chains derive from a common ancestor by somatic mutation of a small number of genes or by gene doubling and selection in the course of evolution. The isolation of the N-terminal peptide in methionine-containing Bence-Jones proteins is also described.

Amino Acid Sequence↗
PubMedDate not supplied

Monoclonal antibodies and cell surface antigens.

Antibody chains are encoded in three gene clusters containing genes for the variable and constant regions. V and C genes are separated in germ line and during differentiation a rearrangement takes place. But even after this rearrangement the V and C coding sequences are not contiguous. A final splicing must take place in committed cells between the transcription of a discontinuous V-and C-region DNA and the expression of a continuous mRNA coding for an antibody chain. Analysis by cell fusion indicates that the splicing is cis. When two antibody-producing cell lines are fused, the resulting hybrids express the two antibodies that characterize the parental lines. Permanent cell lines producing antibody of predefined specificity have now been derived in this way. Spleen cells from hyperimmunized donors are fused with myeloma cells and a proportion of the hybrids that are established synthesize and secrete antibodies directed against the immunogen. The heterogeneous cell population can be cloned and propagated. This is a potent way of producing monospecific antibodies to complex antigens such as cell membranes and transplantation antigens. Monoclonal xenogeneic antibodies to rat cell-surface membranes have proved very valuable for characterizing and separating rat lymphocyte subpopulations. In more recent experiments, monoclonal xenogeneic antibodies to mouse and human cell-surface antigens have also been produced which permit the characterization of the hitherto undescribed differentiation antigens.

Animals↗
PubMedDate not supplied

Use of monoclonal antibodies in immunocytochemistry with special reference to the central nervous system.

Monoclonal antibodies produced by hybrid myelomas have been successfully applied in immunocytochemistry. Here we discuss the results obtained when applying one of these antibodies, to substance P, on tissue sections in conjunction with immunofluorescence and unlabelled immunoenzyme procedures. In addition we discuss a novel approach to the localisation of tissue antigens by using internally labelled, tritiated monoclonal antibodies.

Animals↗
PubMedDate not supplied

mRNA sequences define an unusually restricted IgG response to oxazolone.

The idiotypic analysis of hybridomas derived 7 and 14 days after primary immunization with oxazolone suggested that V-gene expression at these two stages was very different mRNA H and L sequences disclosed that day-7 antibody structures were highly conserved, which can be attributed to the existence of one VH and one VL gene. Conversely, two Ox-id- sequences differed considerably from Ox-id+ antibodies and were apparently unrelated to the previously defined genes.

Animals↗