Hendriks Wouter H, Harding David R K, Rutherfurd-Markwick Kay J
Institute of Food, Nutrition and Human Health, Massey University, Riddet Road, Private Bag 11 222, Palmerston North, New Zealand.
Comp Biochem Physiol B Biochem Mol Biol. 2004 Oct;139(2):245-51. doi: 10.1016/j.cbpc.2004.07.007.
The renal metabolism of the tripeptide, gamma-glutamylfelinylglycine, which our group recently identified in the blood of domestic cats (Felis catus), was investigated. To test our hypothesis that this unique tripeptide is metabolised by the kidney in a similar manner to glutathione-S-conjugates in other animal species, [(35)S]cysteine was administered intraperitoneally to an entire male cat, and urine collected at 1, 4 and 8 h post-injection. Radiolabelled fractions were isolated from the urine following reversed-phase (RP) HPLC. Four [(35)S]radiolabelled fractions were identified and characterised by amino acid analysis, mass spectrometry and comparison of retention times with synthetic compounds (felinine, N-acetyl felinine, felinylglycine, gamma-glutamylfelinylglycine). In addition to the previously described presence of free felinine, we showed the presence of several felinine-containing metabolites, including N-acetyl felinine, felinylglycine and unaltered gamma-glutamylfelinylglycine in cat urine. The results show that renal metabolism of gamma-glutamylfelinylglycine in cats, generally occurs in a similar manner to glutathione S-conjugates in other animal species, although the detection of felinylglycine indicates that subtle differences may exist. Additionally, our research indicates that previously reported estimates of felinine excretion in male cats need to be increased by as much as 54% to account for other felinine containing metabolites in the urine.
我们团队最近在家猫（Felis catus）血液中鉴定出的三肽γ-谷氨酰猫薄荷酰甘氨酸的肾脏代谢情况进行了研究。为了验证我们的假设，即这种独特的三肽在肾脏中的代谢方式与其他动物物种中的谷胱甘肽-S-共轭物相似，将[³⁵S]半胱氨酸腹腔注射给一只雄性家猫，并在注射后1、4和8小时收集尿液。通过反相（RP）高效液相色谱从尿液中分离出放射性标记的组分。通过氨基酸分析、质谱以及与合成化合物（猫薄荷碱、N-乙酰猫薄荷碱、猫薄荷酰甘氨酸、γ-谷氨酰猫薄荷酰甘氨酸）的保留时间比较，鉴定并表征了四个[³⁵S]放射性标记的组分。除了先前描述的游离猫薄荷碱的存在外，我们还表明猫尿液中存在几种含猫薄荷碱的代谢物，包括N-乙酰猫薄荷碱、猫薄荷酰甘氨酸和未改变的γ-谷氨酰猫薄荷酰甘氨酸。结果表明，猫体内γ-谷氨酰猫薄荷酰甘氨酸的肾脏代谢通常与其他动物物种中谷胱甘肽S-共轭物的代谢方式相似，尽管猫薄荷酰甘氨酸的检测表明可能存在细微差异。此外，我们的研究表明，之前报道的雄性猫尿液中猫薄荷碱排泄量的估计值需要增加多达54%，以考虑尿液中其他含猫薄荷碱的代谢物。
