We previously identified DNA sequences involved in the function of the complex promoter of the streptokinase gene from Streptococcus equisimilis H46A, a human serogroup C strain known to express this gene at a high level. As a prerequisite to understanding possible mechanisms that control the balance between the plasminogen activating and plasmin(ogen) binding capacities of H46A, we describe here its gapC gene encoding glyceraldehyde-3-phosphate dehydrogenase (GraP-DH, EC 1.2.1.12), a glycolytic enzyme apparently transported to the cell surface where it functions as a plasmin (ogen) To study the properties of the GapC protein, its gene was inducibly overexpressed in Escherichiu cnli from QIAexpress expression plasmids to yield the authentic GapC or (His),GapC carrying a hexahistidyl N-terminus to permit affinity purification. Both proteins were functionally active, exhibiting specific GraP-DH activities of about 80 kat/mol ( 4 3 0 Uimg) after purification. Their binding parameters [association (k,,) and dissociation (kc,) rate constants, and equilibrium dissociation constants (KCI = k&J] for the interaction with human Gluplasminogen and plasmin were determined by real-time biospecific interaction analysis using the Pharmacia BIAcore instrument. For comparative purposes, the commercial GraP-DH from Bacillus steurothermuphilus (RstGraP-DH), a nonpathogenic organism, was included in these experiments. The K,, values for binding of plasininogen to GapC, (His),GapC and BstGraP-DH were 220 nM, 260 nM and 520 nM, respectively, as compared to 25 nM, 17 nM and 98 nM, respectively, for the binding to plasmin. These data show that both the zymogen and active enzyme posse low-affinity binding sites for the gupC gene product and that the hexahistidyl terminus does not affect function. Prior limited treatment with plasmin enhanced the subsequent plasminogen binding capacity of all three GraP-DHs, presumably by the exposure of new C-terminal lysine residues for binding to the zymogen.Keywcwds: Streptococcus equisimilis; glyceraldehyde-3-phosphate dehydrogenase; gapC gene; plasmin-(ogen)-binding protein.As a major surprise of recent investigations into the nature of cell surface proteins of the pathogenic streptococci, a wallassociated plasmin binding protein has been discovered that structurally and functionally belongs to the glyceraldehyde-3- Ahhrc.iYntions. BHI, brain heart infusion ; GraP-DH, generic abbreviation [or glyceraldehyde-3-phosphate dehydrogenases: BstGraP-DH, GraP-DH from B~d r ' i i s .stearotlirrmr~philu.~ ; IPTG, isopropyl p-u-thiogalactopyranoside; LBS, lysine-binding site; Ni-NTA, Ni2--nitrilotriacetic acid; ~-~~l-Leii-Lys-CH,Cl, i~-valyl-leucyl-lysyI-chloromethanethane.En~rtzes. Glycelaldel?yde-3-phosphate dehydrogenase (EC 1.2.1.12); plasmin (EC 3.4.21.7).Note. The novel nucleotide sequence data published here has been deposited with the EMBLIGenBanWDDBJ sequence data banks and is available under accesibion number X97788. Broder et al. (1991) were the first to purify from the surface of a group A stre...

All‐carbon ladder polymers with extended π systems are of interest for electroluminescence and photovoltaics applications. The synthesis of two new ladder polymers (e.g. see Figure) exhibiting relatively high molecular weights and pronounced film‐forming abilities, is reported. It is also shown that the degree of saturation in these polymers can be chemically closly controlled. magnified image

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Synthesis and characterization of the alkyl chain‐substituted benzodifluoranthene 6 are described. The final synthetic step involves an acid‐promoted dehydration whose conversion is determined to be quantitative. The solubilities of compounds 4e, 5, and 6 are qualitatively correlated with structural features. The molecular structure of 6 in the crystal is elucidated by an X‐ray structure analysis.

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