Proteins - continued lactation

High expression levels of proteins are potentially attained. In many instances, the level of expression exceeds 1 g protein/litre milk. In one case, initial expression levels of 60 g l-1 were observed, which stabilized at 35 g L1 as lactation continued (the expression of the arantitrypsin gene, under the influence of the ovine P-lactoglobulin promoter, in a transgenic sheep). Even at expression levels of 1 g L1, one transgenic goat would produce a similar quantity of product in 1 day as would be likely recoverable from a 50-1001 bioreactor system. 

Under some conditions, the rate of glycolysis from glycogen to lactate plus protons can be greater than the capacity of the transporter to transport all the lactate and protons out of the muscle. In this case, they accumulate in the muscle and the pH falls to about 6.5 or even lower (Chapter 13). This can occur, for example, when a muscle is working close to maximum, or when there is a poor blood supply to a working muscle. If this continued for any length of time, the increase in proton concentration could be sufficient to damage some of the proteins in the muscle. Indeed, if this decrease in pH occurred in the blood, it would be very serious and could rapidly lead to death. This is prevented in two ways ... 

Whey permeate may also be fermented anaerobically to fuel gas. Studies have also been reported on the production of ammonium lactate by continuous fermentation of deproteinized whey to lactic acid followed by neutralization with ammonia. Conversion of whey and whey permeate to oil and single-cell protein with strains of Candida curvata and Trichosporon cutaneum have been examined. Production of the solvents n-butanol and acetone by Clostridium acetobutylicum or C. butyricum is under investigation in New Zealand. Whey permeate also has potential for citric acid and acrylic acid manufacture. Extracellular microbial polysaccharide production from whey permeate has... 

Two moles of lactate are transported to neurons, and metabolized oxidatively to supply ATP for the energy demands of the latter cell [80]. Continuous (4 days) intracerebroventricular lep-tin infusion enhances insulin-stimulated glucose metabolism and favors the expression of the uncoupling proteins UCPl, UCP2 and UCP3 [81]. 

The nephrotoxicity of 16 continues to generate considerable interest. Orellanine was highly toxic to mice (LD50 = 12.5 mg/kg i.p.)[101] and caused interstitial nephritis and tubular necrosis in mouse kidney [102], A summary of 16-induced changes in renal function and morphology has been reported [103]. In LLC-PKi renal epithelial cell cultures, 16 decreased the activity of alkaline phosphatase and lactate dehydrogenase, and decreased the incorporation of H-leucine and H-thymidine [104]. Orellanine was a noncompetitive inhibitor of renal alkaline phosphatase, but a competitive inhibitor of the intestinal and placental enzymes [105]. In canine kidney MDCK cell cultures, 16, or a metabolite of 16, inhibited protein, RNA and DNA synthesis [106]. 

Today, most bipolar ion exchange membranes are industrially used in continuous ion exchange reactions across the membrane by the use of H+ and OH-generated from the bipolar ion exchange membrane. Examples include separation of gluconic acid from gluconate,28 production of amino acids from amino acid salts,29 separation of citric acid from citrate,101 ion exchange of soybean protein,102 and conversion of lactate into lactic acid.82... 

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