Carbon-13 nuclear magnetic resonance (NMR) spectra are reported for vitamin K-dependent peptide (VKP) and profragment-1, both derived from bovine prothrombin. These prothrombin fragments contain γ-carboxyglutamic acid (GLA) residues and it is possible to assign those resonances in the VKP spectrum due to this entity based on comparison with methyl malonic acid and synthetic γ-carboxyglutamic acid derivatives (1). At neutral pH the following assignments (chemical shifts are reported in PPM relative to tetramethylsilane) can be made: carboxyl carbons, 175.8; α-carbon, 58.5; β-carbon, 32.5; γ-carbon, 52.3. These resonance positions depend significantly on pH.
Bibliographical noteFunding Information:
We are indebted to Dr. Norman Boggs for sharing with us his spectroscopic results on Y-carboxyglutamic acid derivatives and to Dr. David Harris for recording the carbon-13 NMR spectra at the Chemistry Department at the University of North Carolina and to Dr. Norman J. Oppenheimer for recording carbon-13 INMRs pectra at the Chemistry Department, Indiana University, Bloomington, Indiana. Furthermore, we wish to thank Professors E. H. Cordes and A. Clouse for their conceptual aid and interest. Purchase of the NMR instrument at UNC was made possible by NSF Instruments Grants GU-2059, 2059-Amendment I, and GP-37602 and by NIH Grant SSOSRR07072.
This work was supported by Grants from the National Institutes of Health (HL 06350 AM 05345 , GM 07966 and HL 15728, a Grant-in-Aid from the North Carolina Heart Association to D.A.G, (MEO78), and the University of North Carolina Hemophilia Developmental Fund, and an Established Investigatorship to Karl A. Koehler from the American Heart Association.