Mammalian tissue

The enzyme system responsible for the biosynthesis of PGs is widely distributed in mammalian tissues and has been extensively studied (2). It is referred to as prostaglandin H synthase (PGHS) and exhibits both cyclooxygenase and peroxidase activity. In addition to the classical PGs two other prostanoid products, thromboxane [57576-52-0] (TxA ) (3) and prostacyclin [35121 -78-9] (PGI2) (4) are also derived from the action of the enzyme system on arachidonic acid (Fig. 1). 

By the turn of the century the theory of chemical mediation of physiologic responses had gained some currency. There ensued in some laboratories an intense search for endogenous chemical modifiers of bodily responses. The first such agent to be isolated from mammalian tissue was the ubiquitous hormone, epinephrine—at that time known as adrenaline. This compound has played an important role in pharmacology as well as in medicinal chemistry. 

Collagen, the principal fibrous protein in mammalian tissue, has a tertiary structure made up of twisted a-helices. Three polypeptide chains, each of which is a left-handed helix, are twisted into a right-handed super helix to form an extremely strong tertiary structure. It has remarkable tensile strength, which makes it important in the structure of bones, tendons, teeth, and cartilage. 

Sorcin (soluble resistance-related calcium binding protein) was isolated from multidrug-resistant cells and is expressed in a few mammalian tissues such as skeletal muscle, heart, and brain. In the heart, sorcin interacts with the ryanodine receptor and L-type Ca2+-channels regulating excitation in contraction coupling. 

Gelatin is a protein, made from the hydrolysis of collagen, a protein that makes up about a third of all mammalian tissue. Collagen is a key component of connective tissues, tendons, and bones. 

Capsaicin is what makes chili peppers hot. It is an irritant, for mammals, but not for birds. This may be because birds spread the seeds better than mammals. It causes a burning sensation in any mammalian tissue with which it comes in contact. 

Advancing the field of process engineering. Important generic goals for research include the development of separation processes for complex and fragile bioproducts the design of bioreactors for plant and mammalian tissue culture and the development of detailed, continuous control of process parameters by rapid, accurate, and noninvasive sensors and instruments. 

The minerals in skeletal mammalian tissues are biological apatites (the plural is used here deliberately because they exist as a continuum of structures... 

Furthermore, any particular type of site belonging to any one of these categories may exist in a number of different cellular or tissue locations. For example, acetylcholinesterase is located in a number of different mammalian tissues (e.g., brain, peripheral nervous system, and red blood cells), and all of these may be inhibited by... 

P-Alanine, a metabolite of cysteine (Figure 34-9), is present in coenzyme A and as P-alanyl dipeptides, principally carnosine (see below). Mammalian tissues form P-alanine from cytosine (Figure 34-9), carnosine, and anserine (Figure 31-2). Mammalian tissues transami-nate P-alanine, forming malonate semialdehyde. Body fluid and tissue levels of P-alanine, taurine, and... 

Figure 31-3. Arginine, ornithine, and proline metabolism. Reactions with solid arrows all occur in mammalian tissues. Putrescine and spermine synthesis occurs in both mammals and bacteria. Arginine phosphate of invertebrate muscle functions as a phosphagen analogous to creatine phosphate of mammalian muscle (see Figure 31-6).

At least seven similar but distinct glucose transporters have been detected to date in mammalian tissues, of which the red cell transporter is one. 

Aplysin has marked effects in mammalian tissue and produces hypotension, bradycardia, neuromuscular paralysis, and contracture of intestinal smooth muscle (85). Aplysiatoxin causes an elevation in blood pressure resistant to adrenoceptor blockade (86). 

Fig. 34.—Circular Dichroism of Glycosaminoglycans (a) Hyaluronic Acid (b) Heparan Sulfate from Normal Mammalian Tissue (c) Chondroitin 4-Sulfate (d) Dermatan Sulfate ...

These are a family of peptides which include substance P, isolated in 1931 but only sequenced in 1971. This peptide has been extensively studied since it was the first major peptide to be extracted from brain but only now are useful antagonists becoming available. Two closely related peptides were then isolated from mammalian tissues and can be added to a number of other tachykinins, many of which are found in amphibians. The name tachykinins originated from the vasoactive effects of substance P but the nomenclature has been resolved into calling the three major mammalian peptides substance P, neurokinin A (NKA) and neurokinin B (NKB) with the corresponding receptors being numbered 1 to 3. The order of potencies at the three receptors as follows ... 

A. Inositol Phosphates.—Phosphatidyl inositol (71) is hydrolysed in mammalian tissues to wyo-inositol 1,2-cyclic phosphate (72).i myoinositol 1-phosphate (73) is released simultaneously but is not converted into (72) by the enzyme system. Periodate oxidation of (73) liberates orthophosphate quantitatively, the unstable dialdehyde phosphate (74) being an intermediate. Little or no orthophosphate is released from glucose 6-phosphate under the same oxidative conditions, and this reaction has been used to assay (73). 

The sarco(endo)plasmic reticulum Ca -ATPases of mammalian tissues can be divided structurally into three main groups (SERCA 1-3) representing the products of different genes (Table I) [8,9,11,53-57]. 

There are at least five distinct isoforms of plasma membrane Ca -ATPases in mammalian tissues that differ in distribution and C-terminal sequences [34]. The molecular weight of these enzymes is in the range of 127 300-134683 (Table I) and they all contain calmodulin-binding domains [3], in contrast to the much smaller ( 110kDa) SERCA enzymes that are calmodulin independent. 

Homologous transporters and their distribution in mammalian tissues... 

These are four monoamines synthesized and seereted within many mammalian tissues, ineluding various regions in the brain, sympathetic nervous system, enlero-chromafhn cells of the digestive tract, and adrenal mednlla. These biogenic amines (indoleamine and catecholamines — dopamine, norepinephrine, and epinephrine) are synthesized within the cell from their precursor amino acids and have been associated with many physiological and behavioral functions in animals and humans. 

Although TLC analysis of vitamin Bj has been reported in food and mammalian tissues, [3,4] we eould not find any arfieles for preparation of vitamin Bj and related compounds using TLC. 

Twarog, B.M., and Page, I.H. Serotonin content of some mammalian tissues and urine and a method for its determination. Am J Physiol 175 157-161, 1953. 

---