• Asian-Australasian Journal of Animal Sciences
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• v.4 no.4
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• pp.369-375
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• 1991

A series of in vitro incubation studies with washed rumen bacteria were conducted to determine the influence of incubation time and concentrations of peptides, alanine, ammonia nitrogen and carbohydrate on the rate of peptide disappearance and on bacterial growth. Disappearance rate of tri-alanine (ala3) under various conditions was between 30.6 and $58.2mg\;hr^-$ per gram bacterial dry matter. Ala3 was removed from the incubation medium in an almost linear fashion as incubation time and ala3 concentration was increased. Washed rumen bacteria utilized ala3 faster than di-l-alanine (ala2) at all concentrations. Adding 9mM carbohydrate significantly increased ala3 disappearance, but level of ammonia nitrogen had no influence on ala3 disappearance. The presence of alanine in the medium significantly lowered ala3 utilization by rumen bacteria. Bacterial dry matter and nitrogen growth yield were not influenced by alanine and peptides when incubation medium already contained a sufficient level of ammonia nitrogen. Increased ammonia nitrogen in the presence of ala3 did not stimulate bacterial growth. Carbohydrate significantly increased bacterial dry matter and nitrogen growth as expected. Results indicate that the rate of peptide utilization by rumen bacteria may be altered by type and concentration of peptides, and energy supply, and this may be mediated through changes in numbers and type of bacteria.

• Asian-Australasian Journal of Animal Sciences
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• v.11 no.2
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• pp.155-161
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• 1998

This study conducted to evaluate effects of popped soybean on levels of ruminal peptides and blood amino acids in Holstein calves fed sudan grass hay as a forage source and popped (PSB) soybean as a concentrate supplement. At 0, 2, 4 and 6 h after feeding, rumen fluid and blood samples were collected from the rumen and jugular vein, respectively, and amino acids, peptides and other nitrogen-containing compounds in the rumen were analyzed. Ruminal pH tended to be higher in the RSB than in the PSB treatments, and declined upto 4 h after feeding, since then increased in both treatments. The concentrations of ammonia-N in all treatments increased upto 2 h after feeding, and then decreased gradually with time after feeding. The concentrations of ammonia N in the rumen were not significantly different between the treatments, however, those in RSB treatment appeared to be higher. Also, protein concentrations in the rumen were not significantly different between the treatments. Peptide productions were the highest at 2 h after feeding in the group fed RSB which is rapidly degradable in rumen, whereas those in the group fed PSB which is slowly degradable in rumen were maximized at 4 h after feeding. The concentration of total free essential amino acids in plasma was higher in the RSB treatment than in the PSB, but disappearance rates of these amino acids out of plasma was higher in the PSB treatment than in the RSB treatment. Disappearance rates of free non-essential amino acids in plasma were not significantly different between the treatments. Consequently, this study implies that the production of peptide and utilization of blood amino acid may be controlled by the modification of protein degradability.

• Animal cells and systems
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• v.4 no.2
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• pp.157-163
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• 2000

Yeast pheromone a-factor is a 13-amino acid peptide hormone that is synthesized as a part of a larger precursor, prepro-$\alpha$-factor, consisting of a signal peptide and a proregion of 64 amino acids. The carboxy-terminal half of the precursor contains four tandem copies of mature $\alpha$-factor. To investigate the molecular basis of intracellular sorting, proteolytic processing, and storage of the peptide hormone, yeast prepro-$\alpha$-factor precursors were heterologously expressed in rat pituitary $GH_3 cells. When cells harboring the precursor were metabolically labeled, a species of approximately 27 kD appeared inside the cells. Digestion with peptide: N-glycosidase F (PNG-F) shifted the molecular mass to a 19 kD, suggesting that the 27 kD protein was the glycosylated form as in yeast cells. The nascent polypeptide is efficiently targeted to the ER in the $GH_3 cells, where it undergoes cleavage of its signal peptide and core glycosylation to generate glycosylated pro-a-factor. To look at the post ER intracellular processing, the pulse-labelled cells were chased up to 2 hrs. The nascent propeptides disappeared from the cells at a half life of 30 min and only 10-25% of the newly synthesized, unprocessed precursors were stored intracellularly after the 2 h chase. However, about 20% of the pulse-labeled pro-$\alpha$-factor precursors were secreted into the medium in the pro-hormone form. With increasing chase time, the intracellular level of propeptide decreased, but the amount of secreted propeptide could not account for the disappearance of intracellular propeptide completely. This disappearance was insensitive to lysosomotropic agents, but was inhibited at $16^{circ}C or 20^{\circ}C$, suggesting that the turnover of the precursors was not occurring in the secretory pathway to trans Golgi network (TGN) or dependent on acidic compartments. From these results, it is concluded that a pan of these heterologous precursors may be processed at its paired dibasic sites by prohormone processing enzymes located in TGN/secretpry vesicles producing small peptides, and that the residual unprocessed precursors may be secreted into the medium rather than degraded intracellularly.

• Journal of Pharmaceutical Investigation
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• v.38 no.3
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• pp.191-197
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• 2008

The purpose of the present study was to examine the pharmacokinetics and lymphatic delivery of the oligopeptide, a model peptide of X antigen epitope peptides, after the intramuscular administration of the peptide-bearing liposomes in rats. $^{14}C$-labelled peptide was used as a tracer to analyze the peptide levels in plasma, bile, urine, tissue homogenates, and lymph nodes (superior cervical nodes, brachial nodes and superior mesenteric nodes). Model peptide rapidly disappeared from the plasma by 30 min (${\alpha}$ phase) after i.v. administration, which was followed by the late disappearance. The apparent plasma half-lives ($t_{1/2({\alpha}),app}$) of the peptide at the ${\alpha}$ phase when administered at a dose of 0.2-1.0 mg/kg were about 5 min. The maximum plasma concentration ($C_{max}$) was $1.52\;{\mu}g/mL$, after the i.m. administration of the peptide at a dose of 1.0 mg/kg. The bioavailability, which was calculated from the time zero to last quantitative time, of the i.m. administered peptide was over 60%. Of the various tissues tested, the peptide was mainly distributed in the kidney after the i.m. administration. The peptide levels in the kidney 3 hr after the i.m. administration were higher than those of maximum plasma concentration ($C_{max}$). The cumulative amounts of the peptide found in the urine 72 hr after the administration of 1.0 mg/kg were 2-folder higher than those in the bile, suggesting that the peptide is mostly excreted in the urine. Moreover, the concentrations of the peptide in the lymph nodes were as high as that of the plasma and the tissues. In conclusion, the peptide concentration in the lymph nodes was maintained by 24 hr after the i.m. administration of the peptide-bearing liposomes.

• Journal of Microbiology and Biotechnology
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• v.23 no.10
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• pp.1386-1394
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• 2013

In our previous study, the 25-mer antimicrobial peptide pleurocidin (Ple) had been thought to induce apoptosis in Candida albicans. This study demonstrated that reactive oxygen species (ROS) production was a major cause of Ple-induced apoptosis. Four truncated analogs were synthesized to understand the functional roles in the N- and C-terminal regions of Ple on the apoptosis. Ple, Ple (4-25), Ple (1-22), and Ple (1-19) produced ROS, including hydroxyl radicals, on the order of [Ple > Ple (1-22) > Ple (4-25) > Ple (1-19)], whereas Ple (7-25) did not induce any ROS production. The results suggested that the N-terminal deletion affected the ROS-inducing activities much more than that of the C-terminal deletion, and net hydrophobicity [Ple > Ple (1-22) > Ple (4-25) > Ple (1-19) > Ple (7-25)] was related to ROS generation rather than other primary factors like net charge. Hence, we focused on the N-terminal-truncated peptides, Ple (4-25) and Ple (7-25), and examined other apoptotic features, including mitochondrial membrane depolarization, caspase activation, phosphatidylserine externalization, and DNA and nuclear fragmentation. The results also confirmed the disappearance of apoptotic activity of Ple (7-25) by the truncation of the N-terminal region (1-6) and the specific activity patterns between Ple and analogs. In conclusion, the N-terminal region of Ple played an important role in apoptosis.

• Journal of the Korean Chemical Society
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• v.32 no.6
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• pp.588-592
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• 1988

A chiral recognition was observed in aminolysis of 3-acyl-4(S)-isopropyl-1,3-thiazolidine-2-thione by racemic amine to give an optically active amide (S-excess) and amine (R-excess). This procedure can be applied to synthesis of macrocyclic diamide macrocyclic spermidine alkaloid, and peptide. The rate of this aminolysis is remarkably affected by steric surrounding; completion of reaction can be easily judged by the disappearance of the original yellow color of 4(S)-AITT. These features of the aminolysis suggested a potential recognition racemic amines by a chiral 4 (S)-AITT derivative. Thus 4 (S)-AITT was synthesized from 4 (S)-isopropyl-1, 3-thiazolidine-2-thione and carboxylic acids.

• Korean Journal of Microbiology
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• v.26 no.4
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• pp.283-290
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• 1988

A spontaneous revertant of mutation rbsB103 that is ribose taxis-positive was characterized. This revertant was found to be export-competent in the export of ribose-binding protein shown by the disappearance of accumulated mutant precursor protein and the export of mature ribose-binding protein to the periplasm. The reversional change was shown to be in the region of risB gene that codes for the amino terminal portion of ribose-binding protein. Analysis by high-performance liquid chromatography of peptide patterns of ribose-binding proteins confirmed the relationship between the wild-type and the revertant proteins as shown for the mutant previously (Iida et al., 1985). When the processing rate of presursor proteins from the wild type and the revertant strain in vivo was compared by pulse-chase experiment, it was found that processing is less efficient than normal in the revertant. Purified mature proteins from both wild-type and revertant were subjected to amino acid sequencing. The results confirmed the amino acid changes deduced from the DNA sequencing and showed that processing of the revertant precursor occured in the correct position even though there are two different amino acids present in the signal sequence.

• Journal of Life Science
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• v.26 no.2
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• pp.164-173
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• 2016

Isotocin (IT), a nonapeptide homolog of oxytocin in mammals, has been suggested to be involved in physiological processes including social behaviors, stress responses, and osmoregulation in teleost fish. To study its structure and function, the gene encoding the IT precursor was cloned from the genomic DNA and brain cDNA of the cinnamon clownfish, Amphiprion melanopus. The IT precursor gene consists of three exons separated by two introns, and encodes an open reading frame of 156 amino acid (aa) residues, comprising a putative signal peptide of 19 aa, a mature IT protein of 9 aa, a proteolytic processing site of 3 aa, and 125 aa of neurophysin. Tissue-specific analysis of the IT precursor transcript indicated its expression in the brain and gonads of A. melanopus. To examine its osmoregulatory effects, the salinity of the seawater (34 ppt) used for rearing A. melanopus was lowered to 15 ppt. Histological analysis of the gills indicated the apparent disappearance of an apical crypt on the surface of the gill lamella of A. melanopus, as pavement cells covered the surface upon acclimation to the lower salinity. The level of Na⁺/K^+-ATPase activity in the gills was increased during the initial stage of acclimation, followed by a decrease to its normal level, suggesting its involvement in osmoregulation and homeostasis. The only slight increase in the level of IT precursor transcript in the A. melanopus brain upon low-salinity acclimation suggested that IT played a minor role, if any, in the process of osmoregulation.