Whitsett J A, Ohning B L, Ross G, Meuth J, Weaver T, Holm B A, Shapiro D L, Notter R H
Pediatr Res. 1986 May;20(5):460-7. doi: 10.1203/00006450-198605000-00016.
Hydrophobic protein of 6,000 and 14,000 daltons was isolated from mammalian pulmonary surfactant obtained from canine, human, and bovine alveolar lavage material. Low molecular weight, hydrophobic, surfactant-associated protein (SAP), herein referred to as SAP 6-14, was distinguished from SAP-35, the major glycoprotein in mammalian surfactants (the 35,000 dalton glycoprotein A or apolipoprotein A) by amino acid composition, peptide mapping, and by resistance of SAP 6-14 to digestion by endoglycosidase F, collagenase, trypsin, and other proteases. The amino acid composition of SAP 6-14 was found to be highly enriched in leucine and other hydrophobic amino acids. The characteristics of protein isolated from bovine replacement surfactant extracts utilized for the treatment of hyaline membrane disease in humans were also studied. SAP 6-14 isolated from calf lung surfactant replacement extracts (CLSE) and surfactant-TA were found to be identical to SAP 6-14 isolated from ether/ethanol extracts of various mammalian surfactants. By contrast, SAP-35, the major surfactant-associated glycoprotein of molecular weight = 35,000, and other higher molecular weight proteins were not detected in significant quantities in the CLSE or surfactant-TA replacement surfactants, either by highly sensitive silver stain analysis or by immunoblot using monospecific antisera generated against bovine SAP-35. Biophysical studies of the CLSE replacement surfactant containing only SAP 6-14 and native phospholipids demonstrated full surface activity compared to natural lung surfactant. Dynamic surface tension lowering and adsorption properties of CLSE were essentially identical to those of freshly isolated bovine whole surfactant. Thus, hydrophobic SAP 6-14 is the only protein detected in bovine lung extract surfactants with full biophysical activity.(ABSTRACT TRUNCATED AT 250 WORDS)
从犬、人及牛肺泡灌洗材料中获得的哺乳动物肺表面活性剂中分离出了分子量为6000和14000道尔顿的疏水蛋白。低分子量、疏水的表面活性剂相关蛋白（SAP），在此称为SAP 6-14，通过氨基酸组成、肽图谱分析以及SAP 6-14对内切糖苷酶F、胶原酶、胰蛋白酶和其他蛋白酶消化的抗性，与哺乳动物表面活性剂中的主要糖蛋白SAP-35（35000道尔顿的糖蛋白A或载脂蛋白A）相区分。发现SAP 6-14的氨基酸组成富含亮氨酸和其他疏水氨基酸。还研究了从用于治疗人类透明膜病的牛替代表面活性剂提取物中分离出的蛋白质的特性。从小牛肺表面活性剂替代提取物（CLSE）和表面活性剂-TA中分离出的SAP 6-14被发现与从各种哺乳动物表面活性剂的乙醚/乙醇提取物中分离出的SAP 6-14相同。相比之下，无论是通过高灵敏度银染分析还是使用针对牛SAP-35产生的单特异性抗血清进行免疫印迹，在CLSE或表面活性剂-TA替代表面活性剂中均未大量检测到分子量为35000的主要表面活性剂相关糖蛋白SAP-35和其他高分子量蛋白。对仅含有SAP 6-14和天然磷脂的CLSE替代表面活性剂的生物物理研究表明，与天然肺表面活性剂相比，其具有完全的表面活性。CLSE的动态表面张力降低和吸附特性与新鲜分离的牛全表面活性剂基本相同。因此，疏水的SAP 6-14是在具有完全生物物理活性的牛肺提取物表面活性剂中检测到的唯一蛋白质。（摘要截于250字）
