Osamu Minowa

Sequence‐specific assignments of downfield‐shifted amide proton resonances of calmodulin Use of two‐dimensional NMR analysis of its tryptic fragments

Two‐dimensional NMR methods were applied to assign the extremely downfield‐shifted amide‐proton resonances in the 500‐MHz 1H‐NMR spectra of the NH2‐terminal fragment of residues 1–75 of calmodulin. The low‐field resonances of the 1H‐NMR spectra of intact calmodulin were assigned to specific amino acid residues by comparison with spectra of the tryptic fragments of residues 1–75 and 78–148, in both the Ca2+‐free and Ca2+‐bound states. The hydrogen bonding of glycine residues connecting the two amino acid residues at the Z and − Y positions in the octahedral Ca2+ coordination site was investigated. The Gly 134 in site IV showed a different property from the other glycines, 25, 61 and 98, involved in sites I, II and III, respectively.

Purification and characterization of α1-thiol proteinase inhibitor and its identity with kinin- and fragment 1·2-free high molecular weight kininogen

1. alpha 1-Thiol proteinase inhibitor (alpha 1 TPI) purified from outdated human plasma was a glycoprotein with Mr 83,000 and was composed of heavy and light chains held together with a disulfide bond. 2. The data on amino acid composition, amino terminal sequence of the light chain and carboxyl terminal sequences of the heavy and light chains indicate that alpha 1 TPI is identical with kinin- and fragment 1.2-free HMW kininogen. 3. Purified human plasmin generated a derivative having the same molecular weight (Mr 83,000), same subunit structure (heavy and light chains) and same inhibitory capacity as alpha 1 TPI from HMW kininogen and kinin-free HMW kininogen. This indicated the possibility that alpha 1 TPI is derived from HMW kininogen by plasmin.