![]() Hyaluronidase increases tissue permeability to accelerate the absorption of other enzymes into tissues. ![]() Amino acid oxidase also triggers some other enzymes and is responsible for the yellow colour of the venom of some species. Amino acid oxidases and proteases are used for digestion. Phospholipase A2 causes hemolysis by lysing the phospholipid cell membranes of red blood cells. Phosphodiesterases interfere with the prey's cardiac system, mainly to lower the blood pressure. Inter- and intra-species variation in venom chemical composition is geographical and ontogenic. Compounds with low molecular weight (up to 1.5 KDa) include metals, peptides, lipids, nucleosides, carbohydrates, amines, and oligopeptides, which inhibit angiotensin-converting enzyme (ACE) and potentiate bradykinin (BPP). Polypeptide toxins (molecular weight 5-10 KDa) include cytotoxins, cardiotoxins, and postsynaptic neurotoxins (such as α-bungarotoxin and α-Cobratoxin), which bind to acetylcholine receptors at neuromuscular junctions. Enzymes ( molecular weight 13-150 KDa) make up 80-90% of viperid and 25-70% of elapid venoms, including digestive hydrolases, L-amino-acid oxidase, phospholipases, thrombin-like pro-coagulant, and kallikrein-like serine proteases and metalloproteinases (hemorrhagins), which damage vascular endothelium. The hundreds, even thousands, of proteins found in venom include toxins, neurotoxins in particular, as well as nontoxic proteins (which also have pharmacological properties), and many enzymes, especially hydrolytic ones. Proteins constitute 90-95% of venom's dry weight and are responsible for almost all of its biological effects. These venoms have been studied and developed for use as pharmacological or diagnostic tools, and even drugs. Some of the proteins in snake venom have very specific effects on various biological functions, including blood coagulation, blood pressure regulation, and transmission of nerve or muscle impulses. Enzymes in venom play an important role in the digestion of prey, and various other substances are responsible for important but non-lethal biological effects. The complex mixture of proteins, enzymes, and various other substances has toxic and lethal properties. Venom contains more than 20 different compounds, which are mostly proteins and polypeptides. The venom is stored in large glands called alveoli before being conveyed by a duct to the base of channeled or tubular fangs through which it's ejected. The glands that secrete zootoxins are a modification of the parotid salivary glands found in other vertebrates and are usually located on each side of the head, below and behind the eye, and enclosed in a muscular sheath. Snake venom is injected by unique fangs during a bite, whereas some species are also able to spit venom. This also provides defense against threats. Snake venom is a highly toxic saliva containing zootoxins that facilitates in the immobilization and digestion of prey. Highly modified saliva containing zootoxins
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