In the present work, aged cotton linters have been analyzed for their chromophore content according to the CRI (''chromophore release & identification'') method. Despite the very low contents in the ppb range, nine chromophores have been unambiguously identified, which makes this account the first one on defined chromophoric structures isolated from cotton. A common feature of the chromophores are 2-hydroxy-[1,4]benzoquinone, 2-hydroxyacetophenone and 5,8-dihydroxynaphthoquinone moieties, which resemble chromophoric structures found in other cellulosic substrates, such as bleached pulps or fibers. The finding of these compounds in lignin-free cotton linters confirms the previous hypothesis that those chromophores are formed from (oxidized) carbohydrate structures rather than from lignin fragments.

A mutant of Bacillus subtilis 6160 that had been isolated by its hyperproduction of a-amylase and protease lacked flagella and motility, and its content of autolytic enzyme(s) was reduced to one-third to one-fourth that of the parent. These phenotypic differences were completely co-transferred by the deoxyribonucleic acid (DNA) of the mutant when five DNA recipient strains of B. subtilis were transformed. The revertants, isolated by motility with a frequency of approximately 10-f, recovered a normal level of autolytic activity and showed reduced productivity of a-amylase and protease. This point mutation allowed normal flagellin synthesis, spore formation, and rate of growth. The comparison of cell envelope of the mutant with that of the parent indicated that there was no significant difference except loss of flagella. Therefore the association at the cell surface of a group of extracellular proteins consisting at least of a-amylase, proteases, flagellin, and autolytic enzyme(s) seem to be coordinately regulated by the gene or seem to be affected coordinately by certain undetected alterations of the cell envelope.Bacillus subtilis produces a variety of extracellular enzymes. For control of the production of extracellular a-amylase in B. subtilis, at least two kinds of genetic characters (amyR and pap) were revealed by Yamaguchi et al. (27,28), Yuki (33), Yoneda et al. (29,30), and Sekiguchi et al. (21). amyR regulated specifically the production of a-amylase, whereas pap affected the production of a-amylase and proteases, but not ribonuclease, simultaneously. B. subtilis YN9, one of the mutants isolated from a transformable strain of B. subtilis by N-methyl-N'nitro-N-nitrosoguanidine treatment, carries a pap mutation and simultaneously produced elevated amounts of a-amylase, alkaline protease, and neutral protease. However, the extent of the elevation was different for each enzyme. Furthermore, the mutant lost its transformability and was different in its cell shape, and the protein component of the membrane preparation was different from that of the parental strain (29). Young (32) and Tomasz and Spizizen (22) reported that the transformability and cell shape of B. subtilis and Pneumococcus were closely related to their autolytic activities.The production of extracellular enzymes seems to vary with alterations not only in environmental conditions but also in the structure and function of the cell envelope (8). Since the autolytic enzyme(s) is responsible for many functions such as the morphogenesis of the cell (5) and the turnover of the cell wall (16), it is quite plausible that the enzyme(s) affects the production of the extracellular enzymes.In this paper we show that the content of the autolytic enzyme(s) in the mutant YN9 is one-third to one-fourth that in the parent 6160.Furthermore, the mutant YN9 lacks flagella and motility, whereas the chemical nature of its cell envelope was similar to that of the parent 6160. The correlation among the clear and significant differences, i.e., the hyperproduction of ...

Hydrogen bonding is important in cellulosic and other carbohydrate structures, but the role of interactions between nonpolar groups is less understood. Therefore, we synthesized cyclohexyl 4'-O cyclohexyl beta-D-cellobioside (8), a molecule that has two glucose rings and two nonpolar cyclohexyl rings. Key to attaching the 4'-Ocyclohexyl group was making the 4'-O,6'-O-cyclohexylidene ketal. After peracetylation, the cyclohexylidene ketal ring was opened regioselectively, providing 65% of 8 after final deacetylation. Comparison of the crystal structure of 8, as the cyclohexane solvate, with those of cellulose and its fragments, especially cellotetraose with four glucose rings, revealed extensive effects from the cyclohexyl groups. Three conformationally unique molecules (A, B, and C) are in the triclinic unit cell of 8, along with two solvent cyclohexanes. When viewed down the crystal's a-axis, the array of C, A, and B looks like the letter N, with A inclined so that its cyclohexyl groups can stack with those of the reducing ends of the B and C molecules. The lower left and upper right points of the N are stacks of cyclohexyl rings on the nonreducing ends of B and C, interspersed with solvent cyclohexanes. Whereas cellotetraose has antiparallel (up-down) packing, A and B in 8 are oriented "down" in the unit cell while C is "up". "Down-down-up" (or, alternatively, "up-up-down") packing is rare for carbohydrates. Other unusual details include 06 in all three staggered orientations: one is tg, two are gg, and three are gt, confirmed with CP/MAS 13C NMR. The tg O6 donates a proton to an intramolecular hydrogen bond to O2', opposite to the major schemes in native cellulose I. A similar but novel O6B-H...O2'B hydrogen bond is based on a slightly distorted gg orientation. The hydrogen bonds between parallel molecules are unique, with linkages between O2'A and O2'B, O3'A and O3'B, and O6A and O6B. Other details, such as the bifurcated O3...O5' and ...O6' hydrogen bonds are similar to those of other cellulosic structures. C-H...O hydrogen bonds are extensive along the [110] line of quarter-staggering. The unusual features described here expand the range of structural motifs to be considered for as-yet undetermined cellulose structures.

Mutants that had a genetic lesion increasing the production of a-amylase and protease simultaneously were isolated from a transformable strain of Bacillus subtilis Marburg by N-methyl-N'-nitro-N-nitrosoguanidine treatment. These mutants produced two to three times more a-amylase and five to 16 times more protease than their parent and were tentatively referred to as AP mutants. As this mutation seems to have occurred at a single gene of the bacterial chromosome and was not located near the a-amylase structural gene, the gene was designated as "pap." When pap-and amyR2 (an a-amylase regulator gene) or pap-and ProH coexisted in the same cell, synergistic effects of the two genetic characters were observed on the a-amylase and protease production, respectively. Upon introduction of the pap mutation, the following phenotypic changes were observed in addition to changes in a-amylase and protease productivity. (i) Mutants lost the character of competence for the transformation. (ii) When cells were cultured at 30 C for 30 h, mutant cells became filament owing to the formation of chains of cells. (iii) Autolysis of cells was decreased in the mutants. When pap was transferred to the wild strain by deoxyribonucleic acid-mediated transformation, the transformants showed all these phenotypic alterations simultaneously.

Previous studies have demonstrated that the principal neutralizing determinant of human iunodeficiency virus type 1 (HIV-1) is located in the V3 loop of glycoprotein gpl20. Antibodies prepared against this region using gp120 or peptides as immunogens have been predonminantly HIV-1-isolate-specific. In the present studies, murine monoclonal antibodies (mAbs) were prepared against the HIV-1MN strain. One mAb, designated NM-01, was selected for its ability to neutralize both the MN and TUB strains. Neutralization of H9-cell infectivity as determined by reverse transcriptase assay demonstrated an lDl5 of <1 jig/ml for both MN and ITB. mAb NM-01 also blocked MN and IIIB infectivity in the MT-2 assay and inhibited their reactivity in syncytium formation. The results further demonstrate that mAb NM-01 binds to the V3 loop of gpl20 at amino acids 312-326. This mAb reacted equally well with loop peptides from the MN, TUB, RF, and CDC4 isolates. In contrast, there was less afflnity with a similar peptide from the NY5 strain and little if any reactivity with ioop peptides from the Z2, Z6, and ELI strains. We also demonstrate that peptides corresponding to the V3 loops of MN and IIIB, but not Z6, block neutralization of TUB virus by mAb NM-O1. These rindings indicate that mAb NM-01 reacts with diverse HIV-1 isolates through the Gly-Pro-Gly-Arg sequence of the V3 loop.Human immunodeficiency virus type 1 (HIV-1) infects a variety oflineages, such as T cells, monocytes/macrophages, and neuronal cells, that express CD4 (1, 2). Studies demonstrating binding of gpl20, the major HIV-1 external envelope glycoprotein, to the CD4 receptor supported the role of this viral glycoprotein in HIV-1 infectivity (3-7). Moreover, several epitopes on gpl20 have been associated with the development of neutralizing antibodies. A conserved domain of gpl20 implicated in HIV-1 infectivity elicits specific neutralization (8). Other conformation-dependent epitopes on gpl20 have resulted in the development of antibodies that broadly neutralize diverse strains of this virus (9, 10). However, the principal neutralizing determinant (PND) has been located in the V3 loop of gp120 (11)(12)(13)(14).The V3 loop consists of a hypervariable 36-amino acid (aa) domain (aa 302-338) that is cross-linked by disulfide bonds (12,14). Recombinant and synthetic protein fragments containing the V3 loop elicit isolate-specific neutralizing antibodies (14-16). More recent studies have demonstrated that the type 2 P-turn structure of the V3 loop, which contains the relatively conserved Gly-Pro-Gly-Arg (GPGR) sequence, is the site recognized by isolate-specific antibodies (11,17). This epitope has been identified by a variety of neutralizing monoclonal antibodies (mAbs) prepared in rodents, whereas other findings indicate that the PND also induces MN-isolatespecific antibodies during HIV-1 infection in humans (18).The hypervariable PND domain may account for the isolatespecific neutralizing activity generated by this epitope. However, several studies have indicated t...