Monomer Choice Influences N-Acryloyl Amino Acid Grafter Conversion via Protease Catalysis.

End-capped peptides modified with reactive functional groups on the N-terminus provide a route to prepare peptide-polymer conjugates for a broad range of applications. Unfortunately, current chemical methods to construct modified peptides rely largely on solid-phase peptide synthesis (SPPS), which lacks green preparative characteristics and is costly, thus limiting its applicability to specialty applications such as regenerative medicine. This work evaluates N-terminally modified N-acryloyl-glutamic acid diethyl ester, N-acryloyl-leucine ethyl ester, and N-acryloyl-alanine ethyl ester as grafters and papain as the protease for the direct addition of amino acid ethyl ester (AA-OEt) monomers via protease-catalyzed peptide synthesis (PCPS) and the corresponding formation of N-acryloyl-functionalized oligopeptides in a one-pot aqueous reaction. It was hypothesized that by building N-acryloyl grafters from AA-OEt monomers that are known to be good substrates for papain in PCPS, the corresponding grafters would yield high grafter conversions, high ratio of grafter-oligopeptide to free NH2-oligopeptide, and high overall yield. However, this work demonstrates based on the grafter/monomers studied herein that the dominant factor in N-acryloyl-AA-OEt grafter conversion is the co-monomer used in co-oligomerizations. Computational modeling using Rosetta qualitatively recapitulates the results and provides insight into the structural and energetic bases underlying substrate selectivity. The findings herein expand our knowledge of factors that determine the efficiency of preparing N-acryloyl-terminated oligopeptides by PCPS that could provide practical routes to peptide macromers for conjugation to polymers and surfaces for a broad range of applications.

Bone tissue, lyophilized and stored at room temperature for 15 days or more, is not capable of transmitting HIV, HCV or HBV.

Over the past 57 years, 17 recipients of frozen bone have been infected with: HIV (Centers for Disease Control and Prevention in Morb Mortal Wkly Rep MMWR 37(39):597-599, 1988; Li et al. in J Formos Med Assoc 100(5):350-351, 2001; Simonds et al. in NEJM 326(11):726-732, 1992; Schratt et al. in Unfallchirurg 99(9):679-684, 1996); HCV (Eggen and Nordbo in NEJM 326(6):411, 1992; Conrad et al. in J Bone Joint Surg Am 77:214-224, 1995; Trotter in J Bone Joint Surg Am 851(11):2215-2217, 2003; Tugwell et al. in Ann of Internal Med 143(9):648-654, 2005); or HBV (Shutkin in J Bone Joint Surg Am 36:160-162, 1954). However, bone, lyophilized and stored at room temperature, has never transmitted these viral diseases. A literature review was undertaken to determine whether there is any evidence that lyophilized bone is capable of transmitting HIV, HCV and HBV.