• Journal of Microbiology and Biotechnology
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• v.25 no.11
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• pp.1827-1834
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• 2015

The SMG1 lipase from Malassezia globosa is a newly found mono- and diacylglycerol (DAG) lipase that has a unique lid in the loop conformation that differs from the common alpha-helix lid. In the present study, we characterized the contribution of three residues, L103 and F104 in the lid and F278 in the rim of the binding site groove, on the function of SMG1 lipase. Site-directed mutagenesis was conducted at these sites, and each of the mutants was expressed in the yeast Pichia pastoris, purified, and characterized for their activity toward DAG and p-nitrophenol (pNP) ester. Compared with wild-type SMG1, F278A retained approximately 78% of its activity toward DAG, but only 11% activity toward pNP octanoate (pNP-C8). L103G increased its activity on pNP-C8 by approximately 2-fold, whereas F104G showed an approximate 40% decrease in pNP-C8 activity, and they both showed decreased activity on the DAG emulsion. The deletion of 103-104 retained approximately 30% of its activity toward the DAG emulsion, with an almost complete loss of pNP-C8 activity. The deletion of 103-104 showed a weaker penetration ability to a soybean phosphocholine monolayer than wild-type SMG1. Based on the modulation of the specificity and activity observed, a pNP-C8 binding model for the ester (pNP-C8, N102, and F278 form a flexible bridge) and a specific lipid-anchoring mechanism for DAG (L103 and F104 serve as "anchors" to the lipid interface) were proposed.

• KSBB Journal
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• v.19 no.2
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• pp.159-163
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• 2004

The X-ray structure of the cydodextrin-glucanotransferase of Bacillus macerans was solved by molecular replacement at 2.0 ${\AA}$ resolution. The refined structure has a crystallographic R-factor of 16.6%, (R$\sub$free/ = 20.5%). A new metal binding site occupied by two Ca$\^$2+/-ions was found at an accession channel of the active site. There is a large accumulation of negative charges that bind these Ca$\^$2+/-ions, thereby connecting segment ${\beta}$13-${\alpha}$G (residue 254-276) to the main body of domain A (at ${\alpha}$H, residue 283-297). The segment 313-${\alpha}$G contains the catalytic residue Glu258 between subsite 1 and -1 and Tyr260 (subsite 2) which is located at the entrance of the active site. The Ca$\^$2＋/-site 3a,b may have a major role for the activity and specificity of this CGTase, although it is not even conserved for the a-subclass of CGTases.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.5 no.1
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• pp.33-45
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• 1998

The aim of this study was to investigate what is the most accurate and quick temperature measurement among rectal, auxiliary and tympanic routes. The body temperatures of 86 preform infants in incubators, a controlled environment, were measured at three different sites. The measurements were taken to examine the accuracy of the temperatures, proper nursing time for measuring the temperatures and the validity of fever detection. The results were as follows : 1. The mean temperature was significantly lower in the auxiliary site($36.71^{\circ}C$) and higher in the tympanic site($37.27^{\circ}C$) than in the rectal site($37.03^{\circ}C$). 2. The mean nursing time for measuring body temperature was significantly longer in the auxiliary site(171.65 seconds) and shorter in the tympanic site(17.70 seconds) than in the rectal site(83.33 seconds). 3. The nursing time for measuring body temperature included the time needed for preparation, measuring, as well as the post-measuring time. It was found that the time required to prepare for measuring the temperature of the rectal site was significantly longer than for other sites. In addition, the time needed to measure the temperature of the auxiliary site was significantly longer than in the other sites. Finally, the nursing time needed for measuring the auxiliary temperature(171.65 seconds) was the longest among the three sites whereas the nursing time for the tympanic site was the shortest(17.70 seconds). 4. Rectal temperature was significantly correlated to the tympanic(r=0.67) and auxiliary temperatures(r=0.69). Tympanic temperature was also significantly correlated to the auxiliary temperature(r=0.74). 5. The sensitivity, specificity, positive and negative predictive values of tympanic temperatures for detecting fever were 1.00, 0.80, 0.24, and 1.00, respectively. Those for the auxiliary temperatures were 0.00, 0.99, 0.00, and 0.94, respectively. Thus the level of fever detection was lower in the auxiliary temperatures than in tympanic temperatures. The above findings indicate that the tympanic method of temperature measurement offers a useful alternative to conventional methods.

• 한국생물공학회:학술대회논문집
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• 2001.11a
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• pp.656-659
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• 2001

Cyclodextrin glucanotransferase (CGTase) (EC 2.4.1.19) use starch to produce cyclic maltooligosaccharides (cyclodextrins, CDs) which are of interest in various applications. To obtain a novel CGTase having high CD-forming activity, ${\beta}-cyclodextrin$ glucanotransferase $({\beta}-CGTase)$ from Bacillus firmus var. alkalophilus was modified through site-directed mutagenesis and constructed five mutants, H59T, H59Q, Y96M, 9O-PPI-93, and ${\Delta}(148-154)D$, respectively. Y96M and ${\Delta}(148-154)D$ showed much higher level of conversion yields of starch into CDs from 28.6% to about 39% compared to wild-type ${\beta}-CGTase$, respectively, but 90-PPI-93 maintained similar convesion yields of starch to CDs. And their ${\beta}-CD$ ratios to total CDs were not changed and maintained, and convesion yields to linear maltooligosaccharides of all mutants were not changed significantly. These results indicates that five mutations of ${\beta}-CGTase$ from Bacillus firmus var. alkalophilus appears to be important roles for increase of overall CD production rather than change of its product specificity, especially.

• Journal of Microbiology and Biotechnology
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• v.30 no.1
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• pp.146-154
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• 2020

With the advantages of biocatalytic method, enzymes have been excavated for the synthesis of chiral amino acids by the reductive amination of ketones, offering a promising way of producing pharmaceutical intermediates. In this work, a robust phenylalanine dehydrogenase (PheDH) with wide substrate spectrum and high catalytic efficiency was constructed through rational design and active-site-targeted, site-specific mutagenesis by using the parent enzyme from Bacillus halodurans. Active sites with bonding substrate and amino acid residues surrounding the substrate binding pocket, 49L-50G-51G, 74M,77K, 122G-123T-124D-125M, 275N, 305L and 308V of the PheDH, were identified. Noticeably, the new mutant PheDH (E113D-N276L) showed approximately 6.06-fold increment of k_cat/Km in the oxidative deamination and more than 1.58-fold in the reductive amination compared to that of the wide type. Meanwhile, the PheDHs exhibit high capacity of accepting benzylic and aliphatic ketone substrates. The broad specificity, high catalytic efficiency and selectivity, along with excellent thermal stability, render these broad-spectrum enzymes ideal targets for further development with potential diagnostic reagent and pharmaceutical compounds applications.

• BMB Reports
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• v.47 no.10
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• pp.593-598
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• 2014

RNA polymerase II carboxyl-terminal domain (RNAPII CTD) phosphatases are responsible for the dephosphorylation of the C-terminal domain of the small subunit of RNAPII in eukaryotes. Recently, we demonstrated the identification of several interacting partners with human small CTD phosphatase1 (hSCP1) and the substrate specificity to delineate an appearance of the dephosphorylation catalyzed by SCP1. In this study, using the established cells for inducibly expressing hSCP1 proteins, we monitored the modification of ${\beta}$-O-linked N-acetylglucosamine (O-GlcNAc). O-GlcNAcylation is one of the most common post-translational modifications (PTMs). To gain insight into the PTM of hSCP1, we used the Western blot, immunoprecipitation, succinylayed wheat germ agglutinin-precipitation, liquid chromatography-mass spectrometry analyses, and site-directed mutagenesis and identified the $Ser^{41}$ residue of hSCP1 as the O-GlcNAc modification site. These results suggest that hSCP1 may be an O-GlcNAcylated protein in vivo, and its N-terminus may function a possible role in the PTM, providing a scaffold for binding the protein(s).

• Journal of architectural history
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• v.9 no.1 s.22
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• pp.47-64
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• 2000

The Chapel and Exhibition hall of Chul-du-san-Holy place are considered as the most important work of architect Lee Hee-Tai (1925-1980), and as a work representing Korean architecture in 1960's. What is the reason that these buildings can acquire such a remarkable estimation? This study tries to make clear this reason with an analytic method. These buildings are situated in singular site, in which small mountain comes up alongside with Han-river. Architect laid out the Chapel and Exhibition hall to the memory of 108 saints who died for their faith in this mountain, considering the specificity of the site, the direction of approach stair, and the formation of public space. Architect proposes an opposed composition of form for these two buildings. So the Exhibition hall is characterized by trabeated structure, centripetal force and Apollonian order. It has strictly proportioned facade, which is composed of two 15m-by-l5m squares and subdivided equally in three portions. The Chapel is charaterized by arcuated structure, centrifugal force, and Dionysosian sentiment. In this work, architect Lee Hee-Tai also expressed the locality of Korean architecture with the grammar of column-roof.

• Journal of Microbiology and Biotechnology
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• v.28 no.8
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• pp.1339-1345
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• 2018

2-Keto-3-deoxy-6-phosphogluconate (KDPG) aldolase, which catalyzes aldol cleavage and condensation reactions, has two distinct substrate-binding sites. The substrate-binding mode at the catalytic site and Schiff-base formation have been well studied. However, structural information on the phosphate-binding loop (P-loop) is limited. Zymomonas mobilis KDPG aldolase is one of the aldolases with a wide substrate spectrum. Its structure in complex with the substrate-mimicking 3-phosphoglycerate (3PG) shows that the phosphate moiety of 3PG interacts with the P-loop and a nearby conserved serine residue. 3PG-binding to the P-loop replaces water molecules aligned from the P-loop to the catalytic site, as observed in the apostructure. The extra electron density near the P-loop and comparison with other aldolases suggest the diversity and flexibility of the serine-containing loop among KDPG aldolases. These structural data may help to understand the substrate-binding mode and the broad substrate specificity of the Zymomonas KDPG aldolase.

• Bulletin of the Korean Chemical Society
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• v.33 no.6
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• pp.1885-1889
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• 2012

Among 23 cytochrome P450s, CYP125A4 was proposed as a putative monooxygenase based on the high level of amino acid sequence homology (54% identity and 75% similarity) with the well characterized C27-steroid $Mycobacterium$ $tuberculosis$ CYP125A1. Utilizing MTBCYP125A1 as a template, homology modeling of SPCYP125A4 was conducted by Accelrys Discovery Studio 3.1 software. The modeled SPCYP125A4 structure with lowest energy value was subsequently assessed for its stereochemical quality and side-chain environment. The final model was generated by showing its active site through the molecular dynamics. The docking of steroids showed broad specificity of SPCYP125A4 with different orientation of ligand within active site facing the heme. One poses of C27-steroid with C26 facing the heme with distance of 3.734 ${\AA}$ from the Fe were predominant.

• Bulletin of the Korean Chemical Society
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• v.22 no.1
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• pp.77-83
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• 2001

To gain further insight into the relationship between structure and function of glutathione S-transferase (GST), the four cysteine mutants, C14S, C47S, C101S and C169S, of human GST P1-1 were expressed in Escherichia coli and purified to electrophoretic homogeneity by affinity chromatography on immobilized glutathione (GSH). The catalytic activities of the four mutant enzymes were characterized with five different substrates as well as by their binding to four different inhibitors. Cys14 seems to participate in the catalytic reaction of GST by stabilizing the conformation of the active-site loop, not in the GSH binding directly. The substitution of Cys47 with serine significantly reduces the affinity of GSH binding, although it does not prevent GSH binding. On the other hand, the substitution of Cys101 with serine appears to change the binding affinity of electrophilic substrate by inducing a conformational change of the $\alpha-helix$ D. Cys169 seems to be important for maintaining the stable conformation of the enzyme. In addition, all four cysteine residues are not needed for the steroid isomerase activity of human glutathione S-transferase P1-1.