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本文从市售田菁粉中分离出半乳甘露聚糖,经纯化分级后得到分子量从1.78×10~3到9.8×10~3的七个级分。用粘度法、小角光散射法和广角激光光散射法测定了各个级分在水中25℃时的[η]、M_(?)、A_2和R_g,得到它们与分子量的关系为[η]=1.88×10~(-2)M~(-0.3),A~2=3.55×10~(-3)M~(-0.65),R_g=4.70×10~(-2)M~(0.56);利用[η]/M~(1/2)=φ(r_o~2/M)~(3/2)+BM~(1/2)求得r_o~2/M=0.0145(nm~2);利用R_g~2/M=R-(gO)~2/M+K(R_(gO)~2)~5/2 M~2/R_g~3求得R_(gO)~2/M=0.0067(nm~2),α=0.518M~(0.06);利用Yamakawa-Fujii-Bohdanecky的蠕虫型圆柱体模型求得:M_2=457(nm~(-1)),(r_o~2/M)_∞=0.0167(nm~2)λ~(-1)=7.63(nm),ρ=3.82(nm),d=0.82(nm),L=2.19×10~(-3)M,C_∞=14.8,证明半乳甘露聚糖的主链略带刚性,但比三硝基纤维素柔软,可以用蠕虫状模型处理。
In this paper, galactomannan was isolated from the commercially available Sesbania powder, and seven fractions with a molecular weight of 1.78 × 10 ~ 3 to 9.8 × 10 ~ 3 were obtained after purification and classification. The [η], M _ (_), A_2 and R_g of each fraction in water at 25 ° C were measured by the viscosity method, small angle light scattering method and wide-angle laser light scattering method, and their relationship with the molecular weight was obtained. (-0.3), A ~ 2 = 3.55 × 10 ~ (-3) M ~ (-0.65) and R_g = 4.70 × 10 ~ (-2) M ~ (0.56) r_o ~ 2 / M = 0.0145 (nm ~ 2) is obtained from [η] / M 1/2 = φ r_o ~ 2 / M ~ 3/2 + BM 1/2; (GO) ~ 2 / M = 0.0067 (nm) is obtained from R_g ~ 2 / M = R- (gO) ~2 / M + K (R_ (gO) ~2) ~5 / 2M ~ 2 / R_g ~ ~ 2) and α = 0.518M ~ (0.06). The worm-type cylindrical model of Yamakawa-Fujii-Bohdanecky was used to calculate the M_2 = 457 nm -1, r_o ~ 2 / M_∞ = 0.0167 λ ~ -1 = 7.63 nm, ρ = 3.82 nm, d = 0.82 nm, L = 2.19 × 10 -3 M, C_∞ = 14.8 The backbone of galactomannan is slightly rigid, but softer than trinitroflocin and can be treated with a worm-like model.