Paoletti Maurizio G, Norberto Lorenzo, Damini Roberta, Musumeci Salvatore
Department of Biology, Laboratory Agroecology and Ethnobiology, University of Padova, Padova, Italy.
Ann Nutr Metab. 2007;51(3):244-51. doi: 10.1159/000104144. Epub 2007 Jun 18.
Chitin digestion by humans has generally been questioned or denied. Only recently chitinases have been found in several human tissues and their role has been associated with defense against parasite infections and to some allergic conditions. In this pilot study we tested the gastric juices of 25 Italian subjects on the artificial substrates 4-methylumbelliferyl-beta-D-N,N',diacetylchitobiose or/and fluorescein isothiocyanate (FITC) chitin to demonstrate the presence of a chitinase activity. Since this chitinase activity was demonstrated at acidic pH, it is currently referred to acidic mammalian chitinase (AMCase). AMCase activity was present in gastric juices of twenty of 25 Italian patients in a range of activity from 0.21 to 36.27 nmol/ml/h and from 8,881 to 1,254,782 fluorescence emission (CPS), according to the used methods. In the remaining five of 25 gastric juices, AMCase activity was almost absent in both assay methods. An allosamidine inhibition test and the measurement at different pH values confirmed that this activity was characteristic of AMCase. The absence of activity in 20% of the gastric juices may be a consequence of virtual absence of chitinous food in the Western diet.
人类对几丁质的消化作用一直受到质疑或被否定。直到最近，才在人体的几种组织中发现了几丁质酶，其作用与抵御寄生虫感染以及某些过敏状况有关。在这项初步研究中，我们用人工底物4-甲基伞形酮基-β-D-N，N'，二乙酰壳二糖或/和异硫氰酸荧光素（FITC）几丁质检测了25名意大利受试者的胃液，以证明几丁质酶活性的存在。由于这种几丁质酶活性是在酸性pH值下被证实的，所以目前被称为酸性哺乳动物几丁质酶（AMCase）。根据所使用的方法，25名意大利患者中有20人的胃液中存在AMCase活性，活性范围为0.21至36.27 nmol/ml/h，荧光发射量（CPS）为8,881至1,254,782。在其余5名患者的胃液中，两种检测方法几乎均未检测到AMCase活性。一种别洛沙米抑制试验以及在不同pH值下的测量结果证实了这种活性是AMCase所特有的。20%的胃液中没有活性，这可能是西方饮食中几丁质类食物实际上不存在的结果。
