Functional groups mammals

Phosphates of pharmaceutical interest are often monoesters (Sect. 9.3), and the enzymes that are able to hydrolyze them include alkaline and acid phosphatases. Alkaline phosphatase (alkaline phosphomonoesterase, EC 3.1.3.1) is a nonspecific esterase of phosphoric monoesters with an optimal pH for catalysis of ca. 8 [140], In the presence of a phosphate acceptor such as 2-aminoethanol, the enzyme also catalyzes a transphosphorylation reaction involving transfer of the phosphoryl group to the alcohol. Alkaline phosphatase is bound extracellularly to membranes and is widely distributed, in particular in the pancreas, liver, bile, placenta, and osteoplasts. Its specific functions in mammals remain poorly understood, but it seems to play an important role in modulation by osteoplasts of bone mineralization. 

Further examples of the importance of functional groups for behavior are the responses of simfish to steroids in beetles, their prey reactions of birds and mammals to capsaicin-related compounds and fear behavior of rats when exposed to sulfur compoimds from fox urine and feces. 

Capsaicin analogues that differ in only one functional group affect birds and mammals differently. A change from an acidic phenolic hydroxyl group in vanil-lyl acetamide to a methoxy group in veratryl acetamide reverses the effect on starlings and rats. The first was aversive to starlings, but attractive to rats, while the opposite was true for veratryl acetamide (Mason etal., 1991). 

Several functional groups, including nitro, azo, tertiary amine N-oxide, aldehyde, ketone, sulfoxide, and alkyl polyhalide, are reduced by mammals in vivo. Toxic free radicals are often formed as intermediates during reduction. Although some of these reactions, or more accurately the initial sequence of the reactions, occur under aerobic conditions in vitro,... 

The mechanisms utilized by plants and mammals in the metabolism of xenoblotlcs are remeirkably similar. Similar classes of compounds or functional groups are frequently metabolized by comparable mechanisms. Oxidation, reduction, hydrolysis, and conjugation reactions occur with similar frequency in both. In most instances, however. 

Nevertheless, current knowledge of biochemical systems and synthetic techniques may allow us to explore them from a slightly different perspective. Namely, what would life look like with an expanded genetic code—that is, with additional amino acids added into the proteins of life. Indeed, over the past few years chemists have been able to utilize native biochemical systems as well as evolved tRNA molecules (which we will discuss in Chapter 25) to load many unique amino acids into proteins of interest at any specific point desired in a number of different cells, including those of yeast, some mammals, and bacteria like E. coli. Some of the unnatural amino acids are shown below. They include ones with unique metals (like selenium), reactive functional groups (such as a ketone and an azide) that can be used for additional chemistry, and a boronic acid that can be used to bind certain sugars covalently. These synthetic amino acids are all derivatives of phenylalanine, but many other amino acid parent structures can be used as well. 

---