Which of the following enzymes is considered most tissue specific?

The choice of Alcohol dehydrogenase (ADH) as the most tissue-specific enzyme is grounded in its distinct biological function and location. ADH is primarily found in the liver where it plays a critical role in the metabolism of alcohol (ethanol) into acetaldehyde. Its presence is significantly high in hepatocytes, and while it can be found in other tissues like the stomach and intestines, its primary association with liver function makes it a key indicator of liver health and function.

In contrast, the other enzymes listed have broader tissue distribution. Creatine kinase (CK) is present in various tissues including muscle, brain, and heart, making it less specific than ADH. Amylase is primarily associated with the pancreas and salivary glands but can also appear in other tissues, limiting its specificity. Alkaline phosphatase (ALP) is found in several tissues, including the liver, bones, kidneys, and bile ducts. This widespread distribution further decreases its specificity relative to ADH.

Thus, the liver-centric role of Alcohol dehydrogenase, paired with its focus on the metabolism of ethanol, solidly positions it as the most tissue-specific enzyme among the options provided.