Metabolism and Hormonal Control of Pectic Substances

Pectic Substances

Pectins are a group of plant polysaccharides whose principal component is 1,4-linked a-d-galactosyluronic acid (O’Neill et al., 1990). Pectins are present in the primary cell walls of all seed-bearing plants and in the junction between cells called the middle lamella. The primary wall surrounds growing plant cells, meristematic cells and cells in succulent tissue such as fruit. The secondary wa...

Apple Fruit Pectic Substances.

1. The pectic substances of apple have been extracted and separated into a pure pectinic acid and a neutral arabinan-galactan complex by precipitation of the acidic component with ethanol and with cetylpyridinium chloride. 2. The composition of the fractions has been determined. The pectinic acid contained galacturonic acid, arabinose, galactose, rhamnose, xylose and several trace sugars. 3. Tr...

Cxxi. the Pectic Substances of Plants

The isolation of pectic substances from softwoods.

Branfoot (1) has summarised the early work on pectic substances. Bonner (2), Norman (3), and Hirst and Jones (4) have reviewed later work on the structure of these substances. Pectic materials that approximate the composition and have some of the properties of pectic acid are widely distributed but in small amounts in mature hardwoods. In 1925 O’Dwyer (5) isolated such a material from beechwood...

Hormonal Control of Glucose Metabolism

Plasma glucose concentration is normally maintained within a narrow range despite wide fluctuations in the supply (meal) and demand (exercise) for nutrients. In adult humans, plasma glucose concentrations throughout a 24-hour period average 90 mg/ dl, with maximum values 60-90 minutes after meals, usually not exceeding 140 mg/ dl, and values during a moderate fast or exercise usually remaining ...