摘要:

AbstractChitosan oligomers of average molecular weight 9300(P9300) and 2200(P2200) were prepared by nitrous acid degradation followed by the reduction of 2,5‐anhydromannose terminal by sodium borohydrate. Although P9300 provided the growth inhibition ofEscherichia coli, P2200 was not growth inhibitor but growth accelerator. The stacking of P9300 to cell wall ofE. coliwas confirmed by the use of FITC(Fluorescein isothiocyanate) labeled chitosan oligomer using the Confocal Laser Scanning Microscope. The permeation of P2200 was also observed through cell wall without stacking to cell wall. The effective growth inhibition of bacteria was assumed to be the prevention of delivery of nutrition through cell wal

ISSN:1022-1360    

DOI:10.1002/masy.19971200103

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractChitin from squid pen was effectively degraded by the chitinase fromBacillussp. PI‐7S, while the degradation of chitin with lysozyme proceeded very slowly. Among the various vital components studied, the degradation of chitin from squid pen was performed not by canine serum, canine tela subcutanea, canine tela liver, and equine serum but by bovine serum and caprine serum. Noteworthy is the fact that chitin sponge subcutaneously implanted in dog reported not to have chitinase was degraded in ca. 14 day

ISSN:1022-1360    

DOI:10.1002/masy.19971200104

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractA new polysaccharide was isolated from the culture ofAcetobacter acetisubsp.xylinum(A. xylinum) NCI 1005 grown on sucrose. The structure of the polymer was analyzed by nuclear magnetic resonance (NMR) spectroscopy. The water‐soluble polysaccharide (WSP) was determined to be β(2, 6) linked polyfructan, which was structurally different from the polymer synthesized from glucose instead of sucrose by the same strain. The discovery of the new polysaccharide has elucidated that the bacterium has the ability to synthesize two different kinds of water‐soluble polysacchar

ISSN:1022-1360    

DOI:10.1002/masy.19971200105

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractStarch is synthesised through the ADP‐glucose pathway, involving the three enzymes ADP‐glucose pyrophosphorylase, starch synthase and starch branching enzyme. ADP‐glucose pyrophosphorylase is the key enzyme of the pathway, determining the flux of carbon into starch. It generates ADP‐glucose, which is the substrate for the starch synthases, from glucose‐1‐phosphate and ATP releasing pyrophosphate. The enzyme is stimulated by 3‐phosphoglycerate and inhibited through inorganic phosphate. The starch synthases, which catalyse the transfer of glucose from ADP‐glucose to the nonreducing end of a growing α‐1,4‐glucan, are divided into two classes, the granule‐bound starch synthases (GBSS) and the soluble starch synthases (SS). In both classes several isoforms have been described from many different plant species. The branching enzyme, which introduces branchpoints into the amylopectin, can also occur in different isoforms. Other enzymes present in plants, which also act on α‐1,4‐glucans, such as the starch phosphorylases, disproportionating enzyme and different starch hydrolases, might also be important for dertermining the starch structure and, therefore, its processibility. Many aspects of starch synthesis are not fully understood to date. Starch metabolism can be manipulated through genetic engineering, either by the ectopic expression of different heterologous genes, or through the repression of the expression of endogenous genes using antisense RNA technology. This not only allows the functional analysis of starch biosynthetic proteins, but also the manipulation of starch structure in order to widen its industrial applications.In this way many different potato lines have been generated, containing either different amounts of starch, or which synthesize a structurally modified starch. These structural changes relate to the amylose content, the phosphate content, or the gelatinisation and gelation ch

ISSN:1022-1360    

DOI:10.1002/masy.19971200106

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractPractically alllow molecular weight surfactantsshow hemolytic activities. Aside of this serious disadvantage almost all low molecular weight solubilizers cause considerable side effects, particularly during or after parenteral application.Polymeric surfactants, however, usually show no or only very little hemolytic effects. They therefore are supposed not to be able to penetrate neither into cellular or erythrocyte walls nor into phospholipid bilayers, resp., similar bilayer membranes due to their large molecular size. Therefore no decay of biological bilayers should be expected with polymeric surfactants. The only pharmaceutically widely used polymeric surfactants are at the moment polyoxyethylene‐polyoxypropylene block copolymers (poloxamers (INN), Pluronicsr̀ and Pluriolsr̀). Unfortunately they have only poor solubility capacities. In order to find better solubilizing polymeric surfactants, some water soluble dextran fatty acid esters (Ref. 1) were synthesized and tested with respect to their solubilisation capacity and hemolytic activity.Usually the hemolytic activity is tested by standard methods using purified animal or human erythrocyte suspensions. As erythrocytes also contain a relatively high amount of lactose dehydrogenase (LDH), we studied the suitability of the highly sensitive, and in the medical diagnostic well known LDH test, as a supplemental hemolytic determination method (Ref. 2). The advantage of this test is, that there is no need of the time consuming purification and standardization as it is required with the erythrocytes' suspension. It can be performed with original blood and without costly preparations at all.The synthesized dextran fatty acid esters proved themselves as very little hemolytic and, compared with the polyoxyethylene‐polyoxypropylene block copolymers, they show improved solubilisation capac

ISSN:1022-1360    

DOI:10.1002/masy.19971200107

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractBecause of a well defined supramolecular architecture of the native starch granules the preparation of molecularly dispersed starch solutions is achieved only after autoclaving at temperatures of 135 to 160 C. A detailed analysis of static light scattering data allowed the determination of the molecular parameters of both the amylopectin and amylose. The results were confirmed by (1) measurements in the iron sodium tartrate complex FeTNa, (2) by extrapolation of the data obtained with degraded starches to no degradation and (3) by sedimentation field‐flow‐fractionation sFFF. Above the overlap concentration strong aggregation due to H‐bonding commenced and eventually led to gelation. The process is promoted by the amylose content and could be followed by static and dynamic light scattering. Cationic starches and cationic amyloses display remarkably different behavior. The branched amylopectin expanded uniformly when the ionic strength was lowered but the corresponding amylose exhibited an unusual helix‐disorder tra

ISSN:1022-1360    

DOI:10.1002/masy.19971200108

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe dilute‐solution behavior and liquid crystal formation of cellulose tris(3,5‐dimethylphenylcarbamate) (CTDC) in 1‐methyl‐2‐pyrrolidone (NMP) at 25°C are discussed by summarizing our recent studies, and its molecular characteristics are compared with those of cellulose tris(phenylcarbamate) (CTC) in the same solvent. The molecular weight dependences of optical anisotropy factor, radius of gyration, intrinsic viscosity ([η]), and isotropic‐cholesteric phase boundary concentration for CTDC are explained consistently by current theories based on the wormlike chain. An analysis of the newly measured [η]for CTC shows that the backbone conformation and chain stiffness are substantially the same for the two cellulose derivatives in NMP. However, a distinct difference in optical anisotropy is found and briefly discussed in relation to the higher optical resolution capacity of CTDC than that of CTC in chromatographic separation of rac

ISSN:1022-1360    

DOI:10.1002/masy.19971200109

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractGellan gum samples having different counterions of TMA+(tetramethyl‐ammonium ion), Na+, K+and Cs+were prepared, and the small‐angle X‐ray scattering was observed from the aqueous solutions of those samples. A sharp peak appears in the SAXS profile at low temperature, indicating the electrostatic interaction between the domains composed of multiple gellan gum chains. The SAXS profile revealed a rigid rod‐like characteristics of gellan gum chain. The cross‐sectional radius of gyration was evaluated from the scattering profiles, and the gelation mechanism was discussed from the change of the cross‐sectional radius of gyration upon gel‐sol transition. Taking the difference of the scattering power of counter ions into account, the ion condensation due to gelation was evaluated from the excess scattering of Cs+gellan gum with respect to K+gellan gum in respective aque

ISSN:1022-1360    

DOI:10.1002/masy.19971200110

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractThe wide applicability of alginates is due to the ease of which gelation can be introduced and that the gelation conditions are compatible with requirements imposed by for instance living cells. The “egg‐box” model describes the gel‐inducing ions embodied in cavities formed by sequences of α‐L‐GulA of the alginate copolymers in a pairing reaction yielding junction zones. Small‐angle X‐ray scattering showed that the cross‐sectional radius of gyration for an alginate with fraction of α‐L‐GulA, FG, = 0.39, increased from Rg,c= 3.5Å for alginate in solution to 7.6Å for homogeneous Ca‐gels at [Ca2+] = 10 mM. The homogeneous Ca‐alginate gels were obtained byin siturelease of Ca2+from Ca‐EGTA or CaCO3using a slowly hydrolyzing lactone. Either increasing the [Ca2+] for a given FGor increasing FGby selection of an alginate from a different seaweed specie and using constant [Ca2+], yielded larger initial slopes and curvature in the cross‐sectional plots of the SAXS data. This indicate the coexistence of junction zones differing in multiplicity characterized by shifting the distribution towards larger multiplicity either for increasing FGor [Ca2+]. The present finding of junction zone formation by lateral condensation of α‐L‐GulA sequences depending on the composition of alginate and Ca‐concentration are significant extensions of the “egg‐box” model that correlate the sequential arrangement of α‐L‐GulA and β‐D‐ManA in alginate to the

ISSN:1022-1360    

DOI:10.1002/masy.19971200111

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY

摘要:

AbstractOrgano‐soluble cellulose‐p‐toluenesulfonates (tosylates) with an insignificant incorporation of chlorodeoxy functions were prepared by reacting cellulose dissolved inN,N‐dimethyl acetamide/LiCl and used as intermediates in the design of cellulosics with new, unusual molecular structures. Thus, the remaining OH groups were acylated and sulfated yielding products with controlled lipophily and amphiphily which are promising polymers for self‐organizing systems. The polarity reversal by tosylation was used for C‐substitution reactions. The molecular structures of the products were proved by FTIR,1H‐ and13C‐N

ISSN:1022-1360    

DOI:10.1002/masy.19971200112

出版商:Hüthig&Wepf Verlag    

年代:1997

数据来源: WILEY