Proteins and carbohydrates

The graphic interface is a multitasking environment that works well. The protein and carbohydrate builders are particularly convenient to use. The small-molecule builder has a selection of common organic functional groups as well as individual atoms for organics and common heteroatoms. There are a... 

Several aspects affect the extent and character of taste and smell. People differ considerably in sensitivity and appreciation of smell and taste, and there is lack of a common language to describe smell and taste experiences. A hereditary or genetic factor may cause a variation between individual reactions, eg, phenylthiourea causes a bitter taste sensation which may not be perceptible to certain people whose general abiUty to distinguish other tastes is not noticeably impaired (17). The variation of pH in saUva, which acts as a buffer and the charge carrier for the depolarization of the taste cell, may influence the perception of acidity differently in people (15,18). Enzymes in saUva can cause rapid chemical changes in basic food ingredients, such as proteins and carbohydrates, with variable effects on the individual. 

The diluent portion also determines the form, or physical appearance, of the flavor, ie, Hquid, powder, or paste. Liquid flavor forms include water-soluble, oil-soluble, and emulsion forms powder flavor forms include plated (including dry solubles), extended, occluded, inclusion complexes, and other encapsulated forms and paste flavor forms include fat, protein, and carbohydrate-based paste. 

Spices and herbs can play an important indirect role in good nutrition. They are not high in nutrient values, but they help to increase the appeal and satisfaction of foods that are highly nutritious. Spices do contain fat, protein and carbohydrates, electrolytic minerals, iron and B vitamins, and others, but even the highest calorie spice, poppy seeds, contains only two to three calories per serving in normal use (12). 

The 4-phosphopantetheine group of CoA is also utilized (for essentially the same purposes) in acyl carrier proteins (ACPs) involved in fatty acid biosynthesis (see Chapter 25). In acyl carrier proteins, the 4-phosphopantetheine is covalently linked to a serine hydroxyl group. Pantothenic acid is an essential factor for the metabolism of fat, protein, and carbohydrates in the tricarboxylic acid cycle and other pathways. In view of its universal importance in metabolism, it is surprising that pantothenic acid deficiencies are not a more serious problem in humans, but this vitamin is abundant in almost all foods, so that deficiencies are rarely observed. 

We ve now covered two of the four major classes of biomolecuies—proteins and carbohydrates—and have two remaining. We ll cover lipids, the largest and most diverse class of biomolecules, in this chapter, looking both at their structure and function and at their metabolism. 

The tiiyroid hormones influence every organ and tissue of tiie body. These hormones are principally concerned with increasing tiie metabolic rate of tissues, which results in increases in tiie heart and respiratory rate, body temperature, cardiac output, oxygen consumption, and the metabolism of fats, proteins, and carbohydrates. The exact mechanisms by which tiie tiiyroid hormones exert their influence 011 body organs and tissues are not well understood. 

At one level, life can be regarded as a collection of hugely complex reactions taking place between organic compounds in oddly shaped containers. Many of these organic compounds are polymers, including the cellulose of wood, natural fibers such as cotton and silk, the proteins and carbohydrates in our food, and the nucleic acids of our genes. 

Lung surfactant is composed mainly of lipid with some proteins and carbohydrate and prevents the alveoli from collapsing. Surfactant activity is largely attributed to dipalmitoylphosphatidylcholine, which is synthesized shortly before parturition in full-term infants. Deficiency of lung surfactant in the lungs of many preterm newborns gives rise to respiratory distress syndrome. Administration of either natural or artificial surfactant has been of therapeutic benefit. 

When compared to whole meal rye flour (280 kcal/1160 kJ) and to wheat flour (320 kcal/1320 kJ), phloem powder (140 kcal/580 kJ) contains approximately 50% less energy. As is typical for all flours, phloem powder also contains a low amount of fat (total amount 2.3 g/100 g). The protein content of phloem is only 2.5 g (per 100 g), whereas the respective amount in whole meal rye flour is 8.8 g and in wheat flour 12.1 g. The content of carbohydrates in phloem ( 30 g/100 g) is about 50% less than in rye (55 g) and wheat flours (59 g). The relatively low energy, protein and carbohydrate content of phloem when compared with commonly used flours, is related to its high content of different fiber. Detailed nutritional data for phloem and phloem breads used in our trial are presented in Table 14.1. 

Polyphenols are ubiquitous in all plant organs where they are found as monomers or in polymerised forms (Schofield et al, 2001). In addition to the beneficial effect of poljq)henols, they also bind minerals and precipitate proteins and carbohydrates, in effect reducing the nutritive value of foods. Polyphenols have been classified for nutritional purposes into extractable and non-extractable types (Bravo, 1998). Extractable polyphenols are low-and intermediate-weight phenolics while non-extractable polyphenols have high molecular weight and are insoluble in normal solvents. 

Somewhat in advance of the widespread usage of the colloidal connotation of Ostwald and others, investigators in a number of instances seem to have favored the view that cellulose, starch, rubber, etc., are polymeric, the term being used in much the same sense as it is used today. The idea that proteins and carbohydrates are polymeric goes back at least to Hlasiwetz and Habermann, who, in 1871, considered... 

In order to define this variety of food matrices, chemical composition differences that primarily influence chemical analytical measurements have to be considered. Major food components determining basic chemical make-up are the proximate composition of fat, protein, carbohydrate, ash, and moisture. Variations in ash content in general have a minor influence on analytical methods for other constituents and impact of moisture content can be controlled. Thus the major components influencing analytical performance are the relative levels of fat, protein, and carbohydrate. 

Southgate (1987) discusses the range of available RMs in terms of their fat, protein, and carbohydrate content. These constituents are presented graphically via a triangle wherein the relative position of each of these three proximate components is represented as 100 % at a separate apex and o % at the opposite side of an equilateral triangle as shown in Figure 6.1. 

Materials of animal origin such as tissue, fat, milk, egg or blood contains usually relatively large amounts of fat, proteins and carbohydrates that need to be reduced during cleanup to allow enrichment of the analytes to be searched for. 

It is debatable whether obesity is related to total calorie intake or composition of macronutrients. Of the three macronutrients (i.e., carbohydrate, protein, and fat), fat has received the most attention given its desirable texture and its ability to augment the flavor of other foods. Food high in fat promotes weight gain in comparison with the other macronutrients because fat is more energy-dense. When compared with carbohydrate and protein, more than twice as many calories per gram are contained in fat. In addition, fat is stored more easily by the body compared with protein and carbohydrate.23... 

Extraction of PHA from plants is likely to be a major factor affecting the production cost of PHA from crops and, therefore, the economic viability of this approach. In contrast to production of PHA from bacterial fermentation, where the production system is designed to produce only PHA, an agricultural production of PHA is likely to be most viable only through the recovery of not only PHA but also all other useful components of the harvested crop, i.e., oil, proteins, and carbohydrates. This fact, combined with the lower level of PHA accumulation in plants in comparison to micro-organism, is likely to make PHA recovery from plants a challenging task. 

Further work both on the protein and carbohydrate constituents is awaited with interest, for it has been shown by Evans and Hauschildt167 that the activity of the hormone of pregnant mares serum is a function Of the whole molecule, inasmuch as it is destroyed both by proteolytic and carbohydrate-splitting enzymes. 

Abstract To understand how membrane-active peptides (MAPs) function in vivo, it is essential to obtain structural information about them in their membrane-bound state. Most biophysical approaches rely on the use of bilayers prepared from synthetic phospholipids, i.e. artificial model membranes. A particularly successful structural method is solid-state NMR, which makes use of macroscopically oriented lipid bilayers to study selectively isotope-labelled peptides. Native biomembranes, however, have a far more complex lipid composition and a significant non-lipidic content (protein and carbohydrate). Model membranes, therefore, are not really adequate to address questions concerning for example the selectivity of these membranolytic peptides against prokaryotic vs eukaryotic cells, their varying activities against different bacterial strains, or other related biological issues. 

The seeds of dicotyledonous plants have two cotyledons, or seed leaves, which are part of the embryo. The cotyledons usually are the main storage tissue, although in some plants (such as castor bean) the endosperm also has a storage function. During development in the field, seeds gradually accumulate storage oils, proteins and carbohydrates (Table 3.1). In the seed, the cotyledon structure is relatively simple. The remainder of the embryo, the embryonic axis, consists mostly of undifferentiated cells, but provascular tissue can be detected that develops into vascular tissue in the seedling. 

The adjuvanticity of liposomes depends upon their composition, number of layers and charge characteristics. They act as effective adjuvants for both protein- and carbohydrate-based antigens and help stimulate both B- and T-cell responses. Their likely mode of action includes depot formation, but they also possibly increase/enhance antigen presentation to macrophages. The exact molecular mechanism(s) by which they stimulate a T-cell response remains to be elucidated,... 

Carpenter et al. [3.18] showed by IR-spectroscopy, that besides the H-bonds between protein and carbohydrate carbohydrate bonds are also necessary to stabilize proteins during drying and reconstitution. 

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