A novel bifunctional reagent: 2,2′-bis(methoxymethylene)- 2,2′-sulfonyldiacetonitrile

Bis[2-(3-carboxyphenoxy)carbonylethyl]phosphinic acid (m-BCCEP): a novel affinity cross-linking reagent for the beta-cleft modification of human hemoglobin

The design and synthesis of bis[2-(3-carboxyphenoxy)carbonylethyl]phosphinic acid (m-BCCEP, 1) as a site-directed affinity reagent for cross-linking human hemoglobin have been reported as part of our long-term goal to generate artificial blood for emergency transfusions. Molecular modeling techniques were used to design the reagent, employing crystal coordinates of human hemoglobin A(0) imported from the Protein Data Bank. It was synthesized in four steps commencing from 3-hydroxybenzoic acid. The reagent 1 was converted to its trisodium salt to allow effective cross-linking in an aqueous medium. The reagent 1, as its trisodium salt, was found to specifically cross-link stroma-free human hemoglobin A(0) in the beta-cleft under oxygenated reaction conditions at neutral pH. The SDS-PAGE analyses of the modified hemoglobin pointed to the molecular mass range of 32 kDa as anticipated. The HPLC analyses of the product suggested that the cross-link had formed between the beta(1)-beta(2) subunits. Molecular dynamics simulation studies on the reagent-HbA(0) complex suggested that the predominant amino acid residues involved in the cross-linking are N-terminus Val-1 or Lys-82 on one of the beta-subunits and Lys-144 on the other. These predictions were borne out by MALDI-TOF MS analyses data of the peptide fragments obtained from tryptic digestion of the cross-linked product. The data also suggested the presence of a minor cross-link between Val-1 and Lys-82 on the opposing subunits. The oxygen equilibrium measurements of the m-BCCEP-modified hemoglobin product at 37 degrees C showed oxygen affinity (P(50) = 25.8 Torr) comparable to that of the natural whole blood (P(50) = 27.0 Torr) and significantly lower than that of stroma-free hemoglobin (P(50) = 14.19 Torr) assayed under identical conditions. The measured Hill coefficient value of 1.91 of the m-BCCEP-modified Hb product points to the reasonable retainment of oxygen-binding cooperativity after the cross-link formation.

Reagents for bioorganic synthesis. 6. The design and synthesis of two novel polyfunctional organic reagents for biomacromolecular modification

The design, synthesis, structure, and properties of two tetrafunctional organic reagents, namely, 2,2'-sulfonylbis[3-(carboxymethylamino)-(E,E)-N-(2-chloroeth yl)propenamide] (SBCCP) (1) and 2,2'-sulfonylbis[3-(carboxymethylamino)-(E,E)-N-(2-oxoeth yl)propenamide] (SBCOP) (2) are reported. Reagents 1 and 2 contain reactive bis(alkyl halide) and bis(aldehyde) functions, respectively, as well as bis(carboxylic acid) moieties. The reagents have potential applications for biomacromolecular cross-linking, in particular for the cross-linking of hemoglobin subunits. Single-crystal X-ray diffraction data of synthetic intermediates (4,5, and 12) provided information about structural features and tether lengths of the target reagents.

A versatile, highly reactive, cross-linking reagent: 2,2'-sulfonylbis[3-methoxy-(E,E)-2-propenenitrile]

Adequate aqueous stability and cross-linking ability of the novel title reagent, recently discovered in this laboratory, have been demonstrated by comparison of its rate of hydrolysis with the rate of reaction with an amine nucleophile and by cross-linking deoxy- and oxyhemoglobins, as an example.