Some venoms also function as digestive fluids.
Beetle PCWDEs are composed of a catalytic domain and of an amino-terminal signal peptide, supporting the secretion of these enzymes from the midgut cells where they are produced to the gut lumen where they exert their biological function as digestive enzymes.
In addition, some c- and i-type lysozymes function as digestive enzymes in insects, for example in Anopheles gambiae[ 63, 64].
Previously, we purified just one lysozyme (i.e., cv-lysozyme 2) from the oyster crystalline style [ 57], indicating cv-lysozyme 3 is not secreted in quantity into the oyster digestive tubules, which will impede its function as a digestive enzyme.
To function as a digestive enzyme, lysozymes must be expressed at high concentration in the stomach and function in the highly acidic and protease-rich environment of that organ [ 10, 42].
Tandem duplication or amplification of the Lyz gene has previously been observed in certain mammals, including the ruminants and rodents, where lysozyme appears to function as a digestive enzyme in the gut [ 3, 25- 34].
However, they are physiologically able to regulate autonomic functions such as digestive tract motility, vascular motility, secretion and absorption [1] [5].
The cathepsin B forms that appear as frequent in juveniles are quite distinct to the cathepsin B transcripts found in the adult stage dataset (Additional Files 7 and 8), suggesting that they might also be functionally distinct; cathepsin B1 functions as a digestive enzyme in the juvenile gut [ 62].
"Now, that's the nose on the clown," he said, adding that -- like ketchup or more tangy dipping sauces -- the condiment also functioned as a digestive aid.
In contrast, ruminants have multiple lysozyme genes [ 4], and at least four code for a gastric lysozyme that functions as a digestive enzyme.
However, it has relatively well-developed lips, forelimbs and shoulders, as well as functioning respiratory, digestive and urinary systems.
