Assembly of synthetic cellulose I.

Lee, Jong H.; Brown, R. Malcolm; Kuga, Shigenori; Shoda, Shin Ichiro; Kobayashi, Shiro

doi:10.1073/pnas.91.16.7425

Cited by 117 publications

(71 citation statements)

References 25 publications

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“…The nonbiological substrate (3-cellobiosyl-fluoride has been shown recently to serve as a substrate for synthesis of cellulose I catalyzed by a purified cellulase in a nonaqueous environment, which favors synthesis rather than hydrolysis of the polymer (Lee et al, 1994). However, the possibility of a glucanase-catalyzed polymerization of cellulose in vivo is a truly novel idea.…”

Section: Tracing the Path Of Carbon Into Cellulosementioning

confidence: 97%

Cellulose biosynthesis.

1995

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Section: Tracing the Path Of Carbon Into Cellulosementioning

confidence: 97%

Cellulose biosynthesis.

1995

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“…Samples were also prepared without application of the mAb/Au solution. Grids were examined using a Philips 420 transmission electron microscope as described by Lee et al [34]. Images of M A 0 B were digitized at 1/30 s and the contrast was enhanced by normalizing the histograms using an IBAS image analysis system 1351.…”

Section: Enzyme Purification Fresh Bovine Liver Was Obtained Frommentioning

confidence: 99%

Monoamine Oxidase B Isolated from Bovine Liver Exists as Large Oligomeric Complexes in Vitro

Shiloff

Behrens

Kwan

et al. 1996

European Journal of Biochemistry

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The quaternary structure and subunit composition of bovine liver monoamine oxidase B (MA0 B) was investigated using size-exclusion chromatography, sucrose gradient centrifugation and electron microscopy. Purified enzyme was subjected to Superdex gel filtration column chromatography in the presence of the non-ionic detergents, n-octyl P-D-glucopyranoside (octyl glucoside) and Triton X-100R-PC (Triton). The specific activity and elution profiles indicate that the enzyme exists as a dimer and preferentially functions as larger oligomeric complexes. Distribution of the oligomeric forms of M A 0 B was found to be dependent upon protein concentration. Dilution of the enzyme, however, had little or no effect upon the specific activity profiles. In Triton and octyl glucoside, plots of specific activity versus molecular mass displayed a sigmoidal shape. The chromatographic data suggest that detergent-solubilized bovine liver M A 0 B exists as cooperative oligomeric enzyme complexes. Similarly, sucrose density gradient centrifugation of purified M A 0 B exhibited a direct correlation between enzyme activity and molecular mass of the M A 0 complexes. M A 0 B activity was found to be widely distributed throughout the sucrose gradient and the highest enzyme activity was contained in the high-density sucrose layers. M A 0 B specific activity is dependent upon the size of the protein complexes and, therefore, oligomerization of the enzyme may play a role in the regulation of M A 0 B. Transmission electron microscopy of purified M A 0 B was performed using protein prepared by octyl glucoside extraction. Purified enzyme was applied to Formvar-coated copper grids and negatively stained with methylamine tungstate. MAO-B-specific monoclonal antibody (MA0 B-1C2) conjugated to colloidal gold was used as a probe. Contrast enhancement of the electron microscopy data showed that detergent-depleted enzyme tends to aggregate in a linear arrangement of oligomeric complexes. Our data suggest that the M A 0 B oligomeric complexes are hexamers which contain threefold rotational symmetry. The individual complexes have globular morphology and the hexamers appear to be composed of a trimer of M A 0 B homodimers.Keywords: membrane protein ; monoamine oxidase ; electron microscopy ; quaternary structure ; proteinprotein interaction.Monoamine oxidase A and B (MA0 A and B) are the major neurotransmitter-metabolizing enzymes located in the outer mitochondria1 membrane of cells in the central nervous system and peripheral tissues [l]. They catalyze the oxidative deamination of neuroactive and vasoactive amines and are thought to play a role in psychiatric and neurological disorders. Defective M A 0 A, due to a single mutation (CAG to TAG) in the gene, has been found in some members of a Dutch family who exhibited abnormally aggressive behavior very high amino acid sequence identity among these three species, particularly in regions of the molecule that bind substrate, inhibitor or the obligatory cofactor, FAD [13]. Site-directed mutagenesis has been u...

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“…Interestingly, cellobiose as an activated compound, in the form of cellobiosyl-fluoride, recently has been used as a direct substrate for a novel assembly of cellulose I (23). In this reaction, the polymerization mechanism can be aptly described as a retaining type.…”

mentioning

confidence: 99%