The distribution of the vitamin K-dependent amino acid, γ-carboxyglutamic acid was examined in proteins from a variety of sources. Proteins examined include purified rat and bovine coagulation proteins, barium citrate-adsorbing proteins from trout plasma, lamprey plasma, earthworm hemolymph, army worm hemolymph, lobster hemolymph, E. coli B/5, soybean leaf, the protein lysate from the hemolymph cell of the horseshoe crab and parathyroid extract. Other purified proteins examined included human α-1-antitrypsin, pepsinogen, S-100, fetuin, tropomyosin-troponin and complement protein C-3. Of these, only the blood-cotting proteins and the vertebrate plasma samples were shown to contain γ-carboxyglutamic acid.
Bibliographical noteFunding Information:
The authors thank the following for the donation of samples for analysis: Dr. Doris Brooker (Limulus cell lysate), Dr. Tim Kurtti (army worm hemolymph), Dr. Ed Elgart (tropomyosin-troponin), Dr. Ed Whitley (al-antitrypsin) and Dr. Brian Tack (complement C-3). This work was supported in part by grant number HL 15728 from the National Institutes of Health.