A modified system for thiazolinone conversion to thiohydantoin derivatives and their separation by high-pressure liquid chromatography

Multi-site-specificity of the vitamin K-dependent carboxylase: in vitro carboxylation of des-gamma-carboxylated bone Gla protein and Des-gamma-carboxylated pro bone Gla protein

The vitamin K-dependent carboxylase processes multiple glutamic acid residues to gamma-carboxyglutamic acid (Gla) residues in a limited number of proteins. The targeted proteins are synthesized with an amino-terminal propeptide which has been shown to play an important role in gamma-carboxylation. The specificity of the enzyme for each potential Gla site, the direction of carboxylation, and the influence of a bound propeptide on these events are not understood. Des-gamma-carboxy forms of bone Gla protein (BGP), which contain potential Gla residues at positions 17, 21, and 24, were employed as model substrates to determine the multi-site-specificity of the enzyme. Recombinant bovine des-gamma-carboxylated proBGP (rdproBGP) and heat-decarboxylated BGP (dBGP), lacking a propeptide, were used as substrates for a bovine liver carboxylase, and the in vitro reaction products were analyzed for the formation of 14CO2 Gla. The di-Gla species was found to be the predominant product of in vitro carboxylation of both rdproBGP and dBGP at less than saturating concentrations of each substrate. Carboxylation of both substrates occurred preferentially at the more C-terminal potential Gla sites, residues 21 and 24. A similar pattern of carboxylation was observed with a rat bone cell carboxylase, suggesting no species or tissue variation in the enzyme specificity. Some tricarboxylated product accumulated during carboxylation of rdproBGP but not dBGP, suggesting that the covalently bound propeptide directs more complete carboxylation of the Gla domain. In addition, monocarboxylated rdproBGP was found to accumulate in the absence but not in the presence of a free noncovalently attached propeptide, indicating that free propeptide affects more efficient carboxylation of rdproBGP.

Characterization of the human myeloid cell nuclear differentiation antigen: relationship to interferon-inducible proteins

The human myeloid cell nuclear differentiation antigen (MNDA) is expressed specifically in cells of the granulocyte/monocyte lineage. The MNDA has been isolated by using a monoclonal antibody affinity matrix and reversed-phase high performance liquid chromatography. Its NH2-terminal sequence has been obtained, as well as additional sequence information derived from peptides produced by cyanogen bromide and SV8 protease cleavages. Meaningful similarities were observed in extended regions between the MNDA and the reported beta interferon-inducible proteins, 202 and 204, from Ehrlich ascites mouse tumor cells. An amphipathic, basic alpha-helical region, showing no similarity to the 202 and 204 proteins, exhibited close similarity to a region in the interferon response factor-2, a protein which binds the interferon stimulated response element. The relatively high number of S(T)PXX motifs present in the partial amino acid sequence of the MNDA, described herein, suggests that the MNDA binds DNA and is a transcription factor.

The principal site of glycation of human complement factor B

Accumulating amino acid sequence data have made it increasingly evident that many essential complement proteins have potentially modifiable lysine residues in putative critical functional regions. Evidence is now presented that glucose is covalently attached to lysine-266 of purified human complement Factor B as a result of glycation. Purified B was treated with NaB3H4, which reduces such bound glucose to a mixture of radiolabelled hexitols. Amino acid analysis revealed the expected radiolabelled hexitol-lysine epimers. In addition, fluorography of dried gels resolving the major high-molecular-mass h.p.l.c.-fractionated CNBr-cleavage peptides of NaB3H4-reduced B indicated that this radioactivity was specifically associated with the 15 kDa fragment derived from the N-terminal region of fragment Bb. Amino acid sequence analysis suggested that the C-terminal lysine (residue 266 of B) of the N-terminal Lys-Lys doublet of this peptide is preferentially modified. If such glycation can subsequently be shown to occur in vivo, then perhaps this modification might also be found to affect the functional activity of B and offer a potential explanation for some of the immunopathological complications of diseases exposing key plasma proteins, such as this active-site-containing proteinase of the multimeric alternative-complement-pathway C3/C5 convertases, to long-term high concentrations of glucose, such as the decreased resistance to infection and impaired chemotaxis and phagocytosis characteristic of diabetes.

Monoclonal antibody 6B6.6 defines a cross-reactive kappa light chain idiotope on human monoclonal and polyclonal rheumatoid factors

Mouse monoclonal antibody (MAb) 6B6.6 was raised against a cross-reactive idiotope (CRI) present on the light chains of 2 human IgM paraproteins with rheumatoid factor (RF) activity. The MAb inhibited the IgG-binding activity of these proteins, and thus appears to react with an epitope located at or near the RF-binding site. Enzyme-linked immunosorbent assay (ELISA) and Western immunoblotting studies indicate that the 6B6.6 CRI is associated with kappa IIIa sub-subgroup light chains, is not related to the Wa, Po, and Bla RF cross-idiotypic specificities, and is clearly distinct from the kappa IIIb-associated CRI detected by MAb 17.109. Using an ELISA, we detected 6B6.6 CRI in 59% of 107 sera and 48% of 50 synovial fluids from patients with seropositive rheumatoid arthritis (RA). However, the quantities of CRI-positive RF were small, and the amount of CRI-positive RF did not correlate with the amount of IgM-RF. The 6B6.6 CRI was shown to occur primarily in the IgM fraction of RA sera by both chromatographic studies and isotype-specific ELISA, although small quantities appeared to be associated with IgA and IgG in some sera. The presence of 6B6.6 CRI on both monoclonal and polyclonal RF is consistent with the view that both are derived, at least in part, from a common gene pool. However, its occurrence in relatively low levels suggests that the number of germline genes encoding for RF is large or that extensive mutation occurs in the course of RF expression in RA.

Characterization of mammalian type IX collagen fragments from limited pepsin digests of a transplantable swarm rat chondrosarcoma

Collagenous fragments from type IX molecules have been solubilized by limited pepsin proteolysis of a transplantable rat chondrosarcoma and isolated by selective salt precipitation. Chromatography of the solubilized precipitate on CM-cellulose under nondenaturing conditions yielded three fractions. When examined by polarimetry, the material in all three fractions revealed native collagen helical structure with melting points which ranged from 31-37 degrees C. When the fractions were denatured and rechromatographed on a column of agarose beads, the most acidic fraction eluted as 13-kDa polypeptides with and without prior reduction and alkylation. In contrast, the second and third fractions eluted as 100-kDa and 30-kDa polypeptides prior to reduction, but on reduction and alkylation produced reducible products of 34 kDa and 10 kDa, respectively. The general compositional features of the three fractions closely resemble comparable collagenous fragments of type IX collagen from other species. The denaturation products of the 13-kDa nonreducible, the 30-kDa reducible, and the 100-kDa reducible fractions were sequentially purified by CM-cellulose and reversed-phase chromatography to resolve the chain constituents. The isolated 10-kDa, 13-kDa, and 34-kDa chains were cleaved with CNBr, and the cleavage products identified by gel-permeation chromatography. Two 13-kDa polypeptides, 13K2 and 13K3, which did not contain any methionyl residues and were not cleaved with CNBr, were digested with trypsin, and the peptide digests were resolved by reversed-phase chromatography. Comparisons of the CNBr and tryptic cleavage products demonstrate that the three major collagenous fragments are composed of three unique polypeptides. A partial amino acid sequence of an 8-kDa CNBr peptide derived from a purified 10-kDa peptide (10K1) matches identically the amino acid sequence derived from a cDNA sequence in the rat alpha 1(IX) chain (Kimura et al., 1989). These studies, then, present convenient procedures useful in the isolation of mammalian type IX collagen fragments and describe features of the rat molecule, indicating that it is similar to the avian counterpart with respect to chain composition and general molecular structure.

Analysis of the spectrin binding domains of globin

This study describes the results of binding studies between human spectrin and peptides obtained by trypsin digestion of human globin. The globin digest when passed through an affinity column of spectrin-coupled sepharose retained one peptide from both alpha and beta chains of globin. The absorbed peptides were eluted with 4 M guanidine hydrochloride and separated on a reverse phase column by high pressure liquid chromatography. Their amino acid sequence was determined and their position located in the globin molecule.

Conversion of the beckman liquid phase sequencer to a gas-liquid phase sequencer

As an effective aid to extend the microsequencing capabilities the Beckman protein/peptide sequenator Series 890C has been successfully converted to a gas-liquid system, in which coupling buffer 25% trimethylamine was employed as a gas, and heptafluorobutyric acid as a liquid. The system has been found to be efficient for microsequencing (less than 100 pmol). The details of mechanical, plumbing, and other minor changes are described in this paper along with the results of sequencing proteins and peptides, directly and from blots.

Purification and primary structure of ostrich insulin

Insulin has been isolated from ostrich pancreas by a procedure of acid ethanol extraction, adsorption onto SP-Sephadex, gel permeation chromatography and HPLC. The primary structure of the ostrich insulin is identical to that reported for the chicken hormone. The isoelectric point as determined by polyacrylamide gel isoelectric focusing was significantly higher than that of the bovine hormone.