Brack C M, Reynolds E C
Infect Immun. 1987 May;55(5):1264-73. doi: 10.1128/iai.55.5.1264-1273.1987.
Rat saliva agglutinated Streptococcus mutans Ingbritt and NCTC 10449 and Streptococcus sanguis NCTC 7864 but not S. mutans NCTC 10921, GS 5, or LM 7, Streptococcus sobrinus 6715-13 or OMZ 65, or Streptococcus cricetus HS 6, as measured turbidometrically. The specificity of agglutination by rat saliva was the same as that by human saliva. Agglutination was associated with a mucin complex (rat salivary agglutinin complex [rS-A]) of sulfated sialoglycoproteins, with a trace of associated lipid and an apparent Mr of 1.6 X 10(6), isolated by gel-filtration Fast Protein Liquid Chromatography. The complex was dissociated in a high-ionic-strength buffer containing 6 M urea and then fractionated by gel filtration and anion-exchange Fast Protein Liquid Chromatography into four sulfated sialoglycoprotein components, designated rS-A-1Q1, rS-A-1Q2, rS-A-1Q3, and rS-A-2, with rS-A-1Q2 being polydisperse through differential glycosylation of the polypeptide backbone. The dissociation destroyed agglutination activity. The polypeptide backbones contained up to 42% serine plus threonine and up to 40% glycine plus alanine plus proline plus valine. The carbohydrate moiety of the rS-A sialoglycoproteins consisted of N-acetylgalactosamine, sialate, galactose, fucose, N-acetylglucosamine, and small amounts of mannose, with the predominant sugar being N-acetylgalactosamine. Agglutination was inhibited by 1 mM EDTA but was restored by 1.5 mM CaCl2. Agglutination was also inhibited by 5 mM CaCl2; nonimmune sera; cationic polymers; and wheat germ, lentil, soybean, and peanut lectins. However, agglutination was not affected by lipoteichoic acid, various anionic proteins, or various sugars. Neuraminidase treatment of rS-A did not affect activity, but tryptic digestion of S. mutans did prevent agglutination. The results are consistent with calcium bridging the negative groups within the rS-A complex and allowing the approach of rS-A to the bacterial cell surface to effect a specific conformational attachment.
通过比浊法测定，大鼠唾液能凝集变形链球菌英布里特株和NCTC 10449以及血链球菌NCTC 7864，但不能凝集变形链球菌NCTC 10921、GS 5或LM 7、远缘链球菌6715 - 13或OMZ 65，或仓鼠链球菌HS 6。大鼠唾液凝集的特异性与人类唾液相同。凝集作用与一种硫酸化唾液糖蛋白的粘蛋白复合物（大鼠唾液凝集素复合物[rS - A]）有关，该复合物含有微量相关脂质，表观分子量为1.6×10⁶，通过凝胶过滤快速蛋白质液相色谱法分离得到。该复合物在含有6 M尿素的高离子强度缓冲液中解离，然后通过凝胶过滤和阴离子交换快速蛋白质液相色谱法分离成四种硫酸化唾液糖蛋白组分，分别命名为rS - A - 1Q1、rS - A - 1Q2、rS - A - 1Q3和rS - A - 2，其中rS - A - 1Q2由于多肽主链的差异糖基化而具有多分散性。解离破坏了凝集活性。多肽主链中丝氨酸加苏氨酸含量高达42%，甘氨酸加丙氨酸加脯氨酸加缬氨酸含量高达40%。rS - A唾液糖蛋白的碳水化合物部分由N - 乙酰半乳糖胺、唾液酸、半乳糖、岩藻糖、N - 乙酰葡糖胺和少量甘露糖组成，其中主要糖类为N - 乙酰半乳糖胺。1 mM EDTA可抑制凝集作用，但1.5 mM CaCl₂可使其恢复。5 mM CaCl₂、非免疫血清、阳离子聚合物以及麦胚凝集素、扁豆凝集素、大豆凝集素和花生凝集素也可抑制凝集作用。然而，脂磷壁酸、各种阴离子蛋白或各种糖类对凝集作用没有影响。用神经氨酸酶处理rS - A不影响活性，但用胰蛋白酶消化变形链球菌确实可阻止凝集。这些结果与钙桥接rS - A复合物内的负基团并使rS - A接近细菌细胞表面以实现特异性构象附着的观点一致。
