No abstract

No abstract

A secretory proteinase inhibitor was isolated from the latex of green fruits of papaya (Curica papaya). The protein exhibited stoichiometric inhibition of bovine trypsin and n-chymotrypsin by the same site or overlapping binding sites. The complete covalent structure consisting of 184 amino acids and two disulfide bonds was determined by protein analysis. During the structural analysis, a procedure was established to separate very hydrophilic peptides by reverse-phase HPLC. The result revealed that the latex protein belongs to an extensively diverse plant protein family that includes inhibitors of serine, cysteine and aspartic proteases, a taste-modifying protein, wound responsive proteins, storage proteins, amylase inhibitors and even an oxidoreductase. In this superfamily, the latex proteinase inhibitor is most similar to the curious protein, miraculin, which makes sour food taste sweet.Two carbohydrate chains, each probably composed of (mannose),, (xylose), , (fucose)o-2, and (Nacetylglucosamine), residues, were attached to asparagine 84 and 90. Mass-spectrometric and compositional analysis suggested that they may represent a new class of plant xylose-containing carbohydrate chains with five mannose residues.

No abstract

SUMMARYWe previously demonstrated a close relationship between the outer membranes of Haemophilus parainfluenzae (HP) antigens (OMHP) and IgA nephropathy (IgAN). Our objective was to clarify the relationship among IgA, IgG, and IgM class antibody against OMHP in the sera of 44 patients with IgAN and 62 patients with other glomerular diseases (OGD) by ELISA. Patients with IgAN showed a significantly higher level of IgA antibodies (P < 0 . 0005) and IgG antibodies (P < 0 . 001) against OMHP, than did patients with OGD. Positive correlations were observed between IgA and IgG antibodies, between IgA and IgM antibodies, and between IgG and IgM antibodies against OMHP in the sera of patients with IgAN. Immunoblotting showed that IgA, IgG, or IgM antibodies against OHMP in the sera of all patients with IgAN bound to the components of OMHP. Amino acid sequences of three components of OMHP recognized by the sera from patients with IgAN revealed homology with those reported for outer membrane protein (OMP) P6 precursor, OMP P5, and P2 porin protein of H. influenzae. Results suggest that patients with IgAN have glomerular deposits of OMP P6 precursor, OMP P5, or P2 porin protein of HP, and a specific increase in the production of IgA antibodies against OMHP via polyclonal activation against these, with switching of production from one isotype to another, e.g. from IgM to IgA.

The high mobility group protein (HMG)-box is a DNA-binding domain found in many proteins that bind preferentially to DNA of irregular structures in a sequence-independent manner and can bend the DNA. We show here that GST-fusion proteins of HMG domains from HMG1 and HMG2 promote a triple-stranded complex formation between DNA containing the (GGA/TCC)11 repeat and oligonucleotides of d(GGA)11 probably due to G:G base pairing. The activity is to reduce association time and requirements of Mg2+ and oligonucleotide concentrations. The HMG box of SRY, the protein determining male-sex differentiation, also has the activity, suggesting that it is not restricted to the HMG-box domains derived from HMG1/2 but is common to those from other members of the HMG-box family of proteins. Interestingly, the box-AB and box-B of HMG1 bend DNA containing the repeat, but SRY fails to bend in a circularization assay. The difference suggests that the two activities of association-promotion and DNA bending are distinct. These results suggest that the HMG-box domain has a novel activity of promoting the association between GGA repeats which might be involved in higher-order architecture of chromatin.

Four proteinase inhibitors, A-II, A-III, B-I, and B-II, were isolated from seeds of Albizzia julibrissin (silk tree) of the subfamily Mimosoideae, which is often regarded as the most primitive group of the Leguminosae plants. They were all of the high-molecular weight type (21,600 for A-II and A-III, and 19,000 for B-I and B-II), and composed of two polypeptide chains, linked together by a disulfide bond. A-II (A-III) inhibited bovine trypsin and alpha-chymotrypsin probably at an identical site. B-I (BII) inactivated bovine alpha-chymotrypsin and porcine elastase. Sequence analyses of A-II and B-II revealed a considerable homology with soybean trypsin inhibitor (Kunitz) but suggested the presence of an about 20-amino acid insertion in the A-II molecule.

No abstract