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Jürgen Beckmann Armin Mehlich Werner Schröder Herbert R. Wenzel Harald Tschesche 《The protein journal》1989,8(1):101-113
The semisynthesis of homologues of aprotinin, the bovine pancreatic trypsin inhibitor, is described. The P1 lysine15 residue was replaced by two methods. The first procedure, which consisted of two enzymatic steps for the incorporation of other amino acids has previously been described. The second approach consisted of six steps of both enzymatic and chemical nature. The modified inhibitor, in which the lysine15-alanine16 peptide bond is hydrolyzed, was used as the starting material. All carboxyl groups of the modified inhibitor were esterified with methanol; the lysine15 methylester group was then selectively hydrolyzed. Afterward, lysine15 itself was split off. Arginine, glutamic acid, methionine, andl-2-aminohexanoic acid (norleucine, Nle) were incorporated using water-soluble carbodiimide combined with an acylation catalyst. The methylester group was used to prevent polymerization. The reactive-site peptide bonds were resynthesized using either chymotrypsin or trypsin. 相似文献
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《Anthrozo?s》2013,26(4):379-385
AbstractThis study was designed to assess the impact of an ongoing pet visitation program on the behavior and emotional state of adjudicated female adolescents at a medium secure residential facility over an eight-week period. To our knowledge, this study is the first randomized trial with a pretest-posttest design aimed at determining whether unstructured animal-assisted activities (AAA) have a positive impact on this unique population of adolescents. Using a random number table, 23 residents were randomly assigned to participate either in the pet visitation program (n = 13) or the facility's usual activities (n = 10). The program entailed weekly one-hour sessions during which participants were involved in activities such as grooming the animals, giving commands, playing fetch, and talking to the animals' handlers. To assess the program's effects on participants' behavior and emotional state, two quantitative instruments, the Youth Self-Report for Ages 11–18 (YSR) and the Resident Behavior Assessment (RBA), and a qualitative survey (designed by the researchers) were administered to the participants both prior to the pet visitation program and following its completion.Results from the two quantitative measures suggested that the pet visitation program did not have a significant effect on the behavior or emotional state of the pet visitation participants. Qualitative results indicated that most of the participants enjoyed some aspect of the pet visitation program. In light of the small sample size and the unanticipated difficulties encountered in the conduct of the study, this research should be considered a pilot study. The limitations inherent to studying the effects of AAA programs in adjudicated adolescents are discussed. 相似文献
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A E Salcini H Chen G Iannolo P De Camilli P P Di Fiore 《The international journal of biochemistry & cell biology》1999,31(8):805-809
Eps15 was originally identified as a substrate for the kinase activity of the epidermal growth factor receptor (EGFR). Eps15 has a tripartite structure comprising a NH2-terminal portion, which contains three EH domains, a central putative coiled-coil region, and a COOH-terminal domain containing multiple copies of the amino acid triplet Aspartate-Proline-Phenylalanine. A pool of Eps15 is localized at clathrin coated pits where it interacts with the clathrin assembly complex AP-2 and a novel AP-2 binding protein, Epsin. Perturbation of Eps15 and Epsin function inhibits receptor-mediated endocytosis of EGF and transferrin, demonstrating that both proteins are components of the endocytic machinery. Since the family of EH-containing proteins is implicated in various aspects of intracellular sorting, biomolecular strategies aimed at interfering with these processes can now be envisioned. These strategies have potentially far reaching implications extending to the control of cell proliferation. In this regard, it is of note that Eps15 has the potential of transforming NIH-3T3 cells and that the eps15 gene is rearranged with the HRX/ALL/MLL gene in acute myelogeneous leukemias, thus implicating this protein in the subversion of cell proliferation in neoplasia. 相似文献
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Jürgen Beckmann Armin Mehlich Werner Schr?der Herbert R. Wenzel Harald Tschesche 《Journal of Protein Chemistry》1989,8(1):101-113
The semisynthesis of homologues of aprotinin, the bovine pancreatic trypsin inhibitor, is described. The P1 lysine15 residue was replaced by two methods. The first procedure, which consisted of two enzymatic steps for the incorporation of other amino acids has previously been described. The second approach consisted of six steps of both enzymatic and chemical nature. The modified inhibitor, in which the lysine15-alanine16 peptide bond is hydrolyzed, was used as the starting material. All carboxyl groups of the modified inhibitor were esterified with methanol; the lysine15 methylester group was then selectively hydrolyzed. Afterward, lysine15 itself was split off. Arginine, glutamic acid, methionine, andl-2-aminohexanoic acid (norleucine, Nle) were incorporated using water-soluble carbodiimide combined with an acylation catalyst. The methylester group was used to prevent polymerization. The reactive-site peptide bonds were resynthesized using either chymotrypsin or trypsin. 相似文献
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《Journal of biomolecular structure & dynamics》1998,15(6):1199-1204
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Following an invasion of exotic annual grasses into California oak woodlands, grass species dominance shifted from native perennials to exotic annuals. In combination with other ecosystem and species characteristics, species-specific N preferences may influence species coexistence and dominance. If species N preferences follow dominance patterns in California oak woodlands, then the more dominant exotic grasses should prefer the most abundant inorganic soil N form (NH4+), while the subordinate native grasses should prefer the less available inorganic (NO3?) or organic (glycine) soil N forms. To investigate this prediction, we applied 15N-labeled NH4+, NO3?, and glycine to soil and measured % 15N recovery by two dominant annual grasses (Bromus diandrus and Bromus hordeaceus) and two subordinate perennial grasses (Elymus glaucus and Nassella pulchra). As expected, shoots of B. diandrus recovered more 15N-NH4+ (74%) than either 15N-NO3? (51%) or 15N-glycine (39%). B. diandrus also captured at least 3.2 times more 15N-NH4+ than subordinate grasses. Dominant B. hordeaceus, however, demonstrated no N form preferences. As hypothesized, shoots of subordinate E. glaucus and N. pulchra recovered 2.1–2.3 times more 15N-NO3? than 15N-NH4+ and increased %N by 4.8–5.7% in response to the application of 15N-NO3?. Both subordinate grasses did not prefer 15N-glycine over 15N-NH4+, suggesting that the importance of this N form in structuring species coexistence in California oak woodlands is minimal. These results support our theory that species N preferences follow dominance patterns in California oak woodlands. To further understand the role of these species-specific N preferences in structuring dominance, the importance of N form versus such characteristics as rooting distribution and species phenologies needs to be explored in the presence of interspecific competition. 相似文献