尿毒症中分子毒物的分离及飞行时间质谱分析

尿毒症被认为是因为患者肾衰而毒素在体内滞留所致^1]。1972年Babb等^2]提出“中分子假说”，认为分子量在300－2000范围内的中等分子量的物质是尿毒症的主要毒性物质。从此，人们作了大量的努力去分离和鉴定尿毒症中分子毒物。然而尿毒症中分子毒物的成分极其复杂^3]，从设定的中分子组分中分离得到的大都是些分子量小于800的小分子物质^4]。因而对中分子假说一直存在争议^5].我们对尿毒症患者及正常人的血清和尿液进行凝胶色谱分离，从尿毒症血清和尿液及正常人尿液中得到两个中分子峰A，B。将不同来源的A峰中的分子毒物进行离子交换色谱的分离和比较，得到了仅存在于尿毒症血清和正常人尿液的A－3亚峰，经脱盐和飞行时间质谱分析，确定了该组分内含有分子分别为839．69，1007．94，2015．16，16，873．69，1106．67和1680．28的6种化合物。

Separation and Analyses of Uremic Middle Molecules by Chromatography and Matrix-assisted Laser Desorption/Ionization Time-of-flight Mass Spectrometry

Sera and urine from patients with severe uremia and healthy subjects were seperated by means of gel permeation chromatography on Sephadex G15 column with N(C₂H₅)₃ H₂CO₃ buffer as eluent. Two middle molecular peaks(A and B) were detected at 206 nm in normal urine, uremic serum and uremic urine, but these two peaks were hardly observed in the profile of normal sera. In contrast, the absorption at 206 nm of fractions Aand Bfrom uremic serum and urine were less than that of fractions Aand Bfrom normal urine. Fractions Afrom normal urine, uremic serum and urine were collected and resolved into 8 to 9 subpeaks at 230 nm by anion exchange chromatography. One of these subpeaks, A-3, was detected in uremic serum and normal urine but undetectable in uremic urine. After a gel permeation chromatography with bidistilled water as eluent for desalting, subfraction A-3 was seperated into two parts designated A-3-Ⅰ and A-3-Ⅱ in order. The results of MALDI-TOF-MSrevealed that the two peaks from both samples were identical respectively, fraction A-3-Ⅰ contained three kinds of components with molecular weight 839.69, 1007.94 and 2015.16 and fraction A-3-Ⅱ consisted of other three kinds of components with molecular weight 873.69, 1106.67 and 1680.28.