• Microbiology and Biotechnology Letters
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• v.22 no.5
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• pp.447-452
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• 1994

The strain SL-387 which produces new inhibitors of aminopeptidase M, MR-387A and B, was isolated from a soil sample. The strain has branched substrate mycelia, from which aerial hyphae develop in the form of open spirals. Spore surface is smooth. Melanoid and soluble pigme- nts were observed. The isolate contains LL-diaminopimelic acid in its cell wall hydrolysate, and has no pectinolytic activity. The strain SL-387 is closely related to Streptomyces griseoruber and S. naganishii, but is different from these strains in some cultural and physiological characteristics. This strain was, therefore, designated as Streptomyces sp. SL-387. The effects of several carbon and nitrogen sources on the production of the inhibitor were examined. Among them, glucose, galactose, mannose, and xylose were effective as a carbon source and soybean meal, soytone, fish meal, and gluten meal were effective as a nitrogen source. The maximum peak of the inhibitor production in jar fermentor was obtained on the fifth day of culture.

• Applied Biological Chemistry
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• v.38 no.2
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• pp.100-105
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• 1995

Media optimization for the production of MR-387A and B, novel aminopeptidase M inhibitors by Streptomyces sp. SL-387 isolated from a soil was studied. Optimized medium was consisted of 1% glucose, 3% soybean meal, 0.2% yeast extract, 0.1% beef extract, 0.3% NaCl, 0.01% $K_2HPO_4$, 0.3% $CaCO_3$, 0.001% $MnCl_2{\cdot}4H_2O$, 0.001% $ZnCl_2{\cdot}7H_2O$, and 0.0005% $MgSO_4{\cdot}7H_2O$, and adjusted to pH 7.0 before autoclaving. When the optimized medium was used as a fermentation medium, maximum productivity of MR-387 was reached at 120 hours of fermentation, and total productivity was 909.1 U/ml.

• Journal of Microbiology and Biotechnology
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• v.6 no.4
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• pp.250-254
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• 1996

MR-387A [(2S, 3R)-2-hydroxy-3-amino-4-phenylbutanoyl-L-valyl-L-prolyl-(2, 4-trans)- L-4-hydroxy-proline] reversibly inhibits aminopeptidase N (BC 3.4.11.2) in a process that is remarkable for its unusual degree of time dependence. The time required to inactivate the enzyme by 50$%$ ($t_{1/2}$) for establishing steady-state levels of $EI^*$complex was approximately 5 minutes. This indicates that the inhibition is a slow-binding process. In dissociation experiments of $EI^*$ complex, enzymic activity was regained slowly in a quadratic equation, indicating that the inhibition of aminopeptidase N by MR-387A is tight-binding and reversible. Thus, the binding of MR-387A by aminopeptidase N is slow and tight, with $K_{i}$ (for initial collision complex, EI) and $K_i{^*}$ (for final tightened complex, $EI^*$) of $2.2\times10^{-8}$ M (from Lineweaver-Burk plot) and $4.4\times10^{-10}$ M (from rate constants), respectively. These data indicate that MR-387A and aminopeptidase N are bound approximately 200-fold more tightly in the final $EI^*$complex than in the initial collision EI complex.

• Microbiology and Biotechnology Letters
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• v.23 no.1
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• pp.47-52
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• 1995

Since the original productivity of new aminopeptidase M inhibitors MR-387A and B by Streptomyces sp. SL-387 (KCTC 0102BP) was not enough for further chemical and biological evaluation, mutation of parent strain by the treatment of N-methyl-N'-nitro-N-nitrosoguanidine was performed in order to obtain a clone with greater inhibitory activity. Mutant N-3 was selected due to a 6-fold greater productivity (40 $\mu$g/ml) than that of the wild type(6.7 $\mu$g/ml). This mutant was resistant to 3,4-dehydro-DL-proline, an antimetabolite of proline, with 25 $\mu$g/ml of minimum inhibitory concentration. Furthermore, the characteristic morphological change from spiral spore chain in wild type to straight in mutant was observed. An aminopeptidase M nhibitor different from MR-387A and B was isolated from the culture broth of the mutant. This inhibitor was composed of 2 proline, 1 valine, and an unknown amino acid which is presumably 3-amino-4-phenylbutanoic acid. IC$_{50}$ value (89.1 $\MU$g/ml) of the purified inhibitor was lower than that of other inhibitors, which may be due to the absence of 2(S)-hydroxyl group within the structure of 3-amino-4-phenyl- butanoic acid.

• Applied Biological Chemistry
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• v.38 no.3
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• pp.196-201
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• 1995

Chemo- and numerical taxonomic studies on the isolate SL-387 producing novel aminopeptidase M inhibitors MR-387A and B were carried out The genus of the isolate was determined as Streptomyces by cultural and morphological data and chemical indices. Forty one taxonomic unit characters were tested for determining the species of the isolate, and the data were analyzed numerically using a computer program as called TAXON. The isolate was best matched to Streptomyces neyagawaensis in the major cluster 18 of Streptomyces with $S_{SM}$ value of 75.67%. On the base of chemotaxonomic data and TAXON analysis, the isolate SL-387 was identified to be a member of Streptomyces neyagawaensis.

• Journal of Microbiology and Biotechnology
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• v.5 no.4
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• pp.213-217
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• 1995

The effect of inorganic phosphate on the fermentative production of aminopeptidase M inhibitors MR-387A and B by Streptomyces sp. SL-387 has been studied. With inorganic phosphate concentrations higher than 0.78 mM, an inverse correlation was found between the maximum inhibitor production and the initial phosphate concentration added. Growth sensitivity of this actinomycete to arsenate, a phosphate analogue, and the use of magnesium carbonate, a phosphate-trapping agent, suggested that the inhibitor formation was under phosphate repression. Exogenous ATP further increased the degree of phosphate interference in both phosphate-repressed and non repressed culture conditions. The use of a phosphate analogue and a protein synthesis inhibitor also suggested that the phosphate itself repressed inhibitor formation.

• Journal of Microbiology and Biotechnology
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• v.6 no.1
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• pp.7-11
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• 1996

MR-387Al (ARPA-Val-Pro) and A2 (AHPA-Val-Hyp) were prepared as aminopeptidase N inhibitors through the synthesis of peptide MR-387A and B analogues which contained 3-amino-2-hydroxy-4-phenyl butanoic acid (ARPA) as a zinc-chelating moiety. They are competitive inhibitors of aminopeptidase N with inhibition constants(Ki) of 4.1 $\times 10^{-7}\;and 1.1 \times 10^{-6}$ M, respectively. MR-387Al also strongly inhibited aminopeptidase B of human myelogenous leukemia K-562 cell with $IC_50$ of 0.35 $\mu$ M. Inhibitions of aminopeptidase N activity by ARPA-bearing inhibitors of various peptide chain lengths also have been studied. $IC_ 50$ values of AHPA-Val (bestatin), ARPA-Val-Pro (MR-387Al) and ARPA-Val-Pro-Leu (MR-387C) compared against porcine kidney aminopeptidase N were 20.1, 0.60 and 0.08 $\mu$ M, respectively. These results support that a multiple interaction between the $S_1\to S'_3$ sites of aminopeptidase N and the $P_1\to P'_3$ of the inhibitor plays a crucial role in stabilizing strongly the enzyme-inhibitor complex.

• Journal of Microbiology and Biotechnology
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• v.5 no.3
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• pp.158-162
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• 1995

The effect of carbon and nitrogen sources on the production of novel aminopeptidase M inhibitors MR-387A and B by Streptomyces sp. SL-387 has been studied. High D-glucose and ammonia concentrations (5$\%$ and 1$\%$, respectively) exerted a negative influence on the inhibitor formation. The suppressive effect of glucose on the inhibitor formation is probably caused by an effect of medium pH rather than that of cyclic AMP. To establish the optimum conditions for inhibitor overproduction, various nitrogen sources and ammonium ion-trapping agents were examined. The use of ammonia slow-releasing nitrogen sources such as soybean meal and fish meal, or ammonium ion-trapping agents such as kaoline, celite, and natural zeolite achieved the enhancement of inhibitor production. These results also indicate that inhibitor formation is affected by ammonium ion repression.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.387-392
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• 2007

The paper presents control performance of a magnetorheological (MR) fluid-based haptic knob which is applicable to invehicle comfort functions. As a first step, MR fluid-based haptic knob is devised to be capable of both rotary and push motions with a single device. Under consideration of spatial limitation, design parameters are optimally determined to minimize a reciprocal of control torque using finite element analysis. The proposed haptic knob is then manufactured and its fielddependent torque is experimentally evaluated. Subsequently, in-vehicle comfort functions are constructed in virtual environment and make them communicate with the haptic knob. Control performances such as reflection force are experimentally evaluated via simple feed-forward control strategy.

• Applied Biological Chemistry
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• v.40 no.5
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• pp.380-387
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• 1997

Phytopathogenic Erwinia carotovora subsp. carotovora (Ecc) LY34 causes plant tissue maceration by secretion of pectinolytic enzymes such as pectate Iyase (PL) existed as multiple isoenzyme form. Genomic DNA from Ecc LY34 was digested with Sau3Al and ligated into the BamHI site of pBluescript ll $SK^+$. Among them, a clone hydrolyzing polypectate was selected and its DNA was digested with BamHI. Through the subsequent subcloning the resulting 3.1 kb fragment, corresponding to a peICI, was subcloned into pLYPA 100. The structural organization of a peICI gene encoding a 374 amino acid residues consists of an open reading frame (ORF) of 1,122 bp commencing with a ATG start codon and followed by a TAA stop codon. PeICI contained a typical prokaryotic signal peptide of 22-amino acid. Since the deduced amino acid sequences of PeICl protein was very similar to those of PelIII of Erwinia carotovora subsp. carotovora, and to those of Pel3 of Erwinia carotovora subsp. atroseptica, and to those of PeIC of Erwinia carotovora subsp. carotovora, it belong to the same family PLbc group. The 374-amino acld PeICI had a calculated Mr of 40,507 and pI of 7.60.