Stegodyphus lineatus
The act of reproduction, regarding the female, leads to an increase of digestive enzymes. This allows her to eat more prey and to stock more nutrients. The digestive enzymes then start to digest the inside of the organism itself, except for the heart, guts, and mostly the ovaries. Once the offspring are born, and until the mother dies, the mother regurgitates for two weeks the fluids stocked inside as highly nutritive food for the progeny. Ninety-five per cent of the mother's mass is digested by the offspring. They will grow to three times their original size between their birth and dispersion. During the period when female spiders are caring for their hatched offspring, the mothers do not eat, and their offspring only eat the food that the mother regurgitates along with the mother's body at the end of this time.
Proteinase K
Activated by calcium, the enzyme digests proteins preferentially after hydrophobic amino acids (aliphatic, aromatic and other hydrophobic amino acids). Although calcium ions do not affect the enzyme activity, they do contribute to its stability.
Proteins will be completely digested if the incubation time is long and the protease concentration high enough. Upon removal of the calcium ions, the stability of the enzyme is reduced, but the proteolytic activity remains. Proteinase K has two binding sites for Ca, which are located close to the active center, but are not directly involved in the catalytic mechanism. The residual activity is sufficient to digest proteins, which usually contaminate nucleic acid preparations. Therefore, the digestion with Proteinase K for the purification of nucleic acids is usually performed in the presence of EDTA (inhibition of calcium-dependent enzymes such as nucleases).