NASA Scientific and Technical Aerospace Reports

looking at data files generated by EUGEN without the necessity of relying on the PV-WAVE based plotting software.
Author
Computer Programs; Preprocessing; Data Processing; Rocket Engines; Engine Tests
20040070912 NASA Marshall Space Flight Center, Huntsville, AL, USA
Structural Basis for the Catalytic Activity of Human SER/THR Protein Phosphatase-5
Swingle, M. R.; Honkanen, R.; Ciszak, E.; [2004]; 1 pp.; In English; No Copyright; Avail: Other Sources; Abstract Only
Serinekhreonine protein phosphatase-5 (PP5) affects many signaling networks that regulate cell growth. Here we report
the 1.6 Angstrom resolution crystal structure of PP5 catalytic domain with metal and phosphate ions in the active site. The
structure reveals a mechanism for PPS-mediated catalysis that requires the precise positioning of two metal ions within a
conserved Asp(sup 271)-M(sub 1),-M(sub 2)-His(sup 427)-W(sup 2)-His(sup 304)-Asp(sup 274) catalytic motif, and provides
a structural basis for the exceptional catalytic proficiency of protein phosphatases placing them among the most powerful
catalysts. Resolution of the entire C-terminus revealed a novel subdomain, and the structure of PP5 should aid development
of specific inhibitors.
Author
Catalytic Activity; Crystal Structure; Proteins; Cells (Biology)
20040070914 NASA Marshall Space Flight Center, Huntsville, AL, USA
Function of Several Critical Amino Acids in Human Pyruvate Dehydrogenase Revealed by Its Structure
Korotchkina, Lioubov G.; Ciszak, E.; Patel, M.; 2004; 2 pp.; In English; No Copyright; Avail: Other Sources; Abstract Only
Pyruvate dehydrogenase (E1), an alpha 2 beta 2 tetramer, catalyzes the oxidative decarboxylation of pyruvate and
reductive acetylation of lipoyl moieties of the dihydrolipoamide acetyltransferase. The roles of beta W135, alpha P188, alpha
M181, alpha H15 and alpha R349 of E1 determined by kinetic analysis were reassessed by analyzing the three-dimensional
structure of human E1. The residues identified above are found to play a structural role rather than being directly involved in
catalysis: beta W135 is the center residue in the hydrophobic interaction between beta and beta’ subunits; alpha P188 and
alpha M181 are critical for the conformation of the TPP-binding motif and interaction between alpha and beta subunits; alpha
H15, is necessary for the organization of the N-terminus of alpha and alpha’; subunits and alpha R349 supports the interaction
of the C-terminus of the alpha subunits with the beta subunits. Analysis of several critical E1 residues confirms the importance
of residues distant from the active site for subunit interactions and enzyme function.
Author
Amino Acids; Enzymes; Pyruvates
20040070916 NASA Marshall Space Flight Center, Huntsville, AL, USA
Enzymatic Properties of an Alkaline and Chelator Resistant Proportional to alpha-Amylase from the Alkaliphilic
Bacillus sp. Isolate L1711
Bernhardsdotter, Eva C. M. J.; Pusey, Marc L.; Ng, Joseph D.; Garriott, Owen K.; 2004; 1 pp.; In English; No Copyright;
Avail: Other Sources; Abstract Only
An alkaliphilic amylase producing bacterium, Bacillus sp. strain L1711, was selected among 13 soda lakes isolates. When
grown at pH 10.5 and 370 C, strain L1711 produced multiple forms of amylases in the culture broth. One of these, BAA, was
purified from the culture supernatant by QAE column chromatography and preparative native gel electrophoresis. The
molecular weight of BAA was determined to be 51 kDa by denaturing gel electrophoresis. The pH optima for activity below
and above 40 C were 9.5-10.0 and 7.0-7.5 respectively. BAA was stable in the pH range 6-11 and was completely inactivated
at 55?C. The thermostability was not increased in the presence of Ca(2+). The enzyme was strongly inhibited by Ca(2+),
Zn(2+), Mg(2+), Mn(2+), Ba(2+) and Cu(2+), whereas the presence of Na(+), Co2+ and EDTA (10 mM) enhanced enzymatic
activity. The K(sub m) and specific activity of BAA on soluble starch were 1.9 mg/ml and 18.5 U/mg respectively. The main
end products of hydrolysis were maltotetraose, maltose and glucose .
Author
Bacillus; Bacteria; Chelation; Enzyme Activity; Enzymes; Ph; Alkalinity
20040070917 NASA Marshall Space Flight Center, Huntsville, AL, USA
Cloning and Characterization of an Alpha-amylase Gene from the Hyperthermophilic Archaeon Thermococcus
Thioreducens
Bernhardsdotter, Eva C. M. J.; Pusey, Marc L.; Ng, Joseph D.; Garriott, Owen K.; [2004]; 1 pp.; In English; No Copyright;
Avail: Other Sources; Abstract Only
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