Benzoyl-CoA then combines the two units to form cocaine. N-methyl-pyrrolinium cation
The biosynthesis begins with L-Glutamine, which is derived to L-ornithine in plants. The major contribution of L-ornithine and L-arginine as a precursor to the tropane ring was confirmed by Edward Leete. Ornithine then undergoes a pyridoxal phosphate-dependent decarboxylation to form putrescine. In some animals, the urea cycle derives putrescine from ornithine. L-ornithine is converted to L-arginine, which is then decarboxylated via PLP to form agmatine. Hydrolysis of the imine derives N-carbamoylputrescine followed with hydrolysis of the urea to form putrescine. The separate pathways of converting ornithine to putrescine in plants and animals have converged. A SAM-dependent N-methylation of putrescine gives the N-methylputrescine product, which then undergoes oxidative deamination by the action of diamine oxidase to yield the aminoaldehyde. Schiff base formation confirms the biosynthesis of the N-methyl-Δ1-pyrrolinium cation. Robert Robinsons acetonedicarboxylate
The biosynthesis of the tropane alkaloid is still not understood. Hemscheidt proposes that Robinsons acetonedicarboxylate emerges as a potential intermediate for this reaction. Condensation of N-methylpyrrolinium and acetonedicarboxylate would generate the oxobutyrate. Decarboxylation leads to tropane alkaloid formation. Reduction of tropinone
The reduction of tropinone is mediated by NADPH-dependent reductase enzymes, which have been characterized in multiple plant species. These plant species all contain two types of the reductase enzymes, tropinone reductase I and tropinone reductase II. TRI produces tropine and TRII produces pseudotropine. Due to differing kinetic and pH/activity characteristics of the enzymes and by the 25-fold higher activity of TRI over TRII, the majority of the tropinone reduction is from TRI to form tropine.
Blood blisters can also occur in the mouth for a variety of reasons including side effects to certain medications, nutritional deficiencies, and mouth injuries. Treatment
There are several methods of healing blood blisters, including elevation of the wound combined with application of a cold pack, and application of padded dressings or splints. See also
Bleeding – Loss of blood escaping from the circulatory system
Blister – Small pocket of fluid within the upper layers of the skin
Bruise – Type of localized bleeding in tissues outside blood vessels
Cherry angioma – Small bright red dome-shaped bump on the skin


== References ==