516. A simple method for preparing crystalline rennin

Berridge, N. J.; Woodward, C.

doi:10.1017/s0022029900006907

Cited by 21 publications

(4 citation statements)

References 4 publications

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“…The final significance of these effects remains unknown. However, as most growth factors have such effects and as Ca'+ is considered to have a key role in the control of proliferation [4,32], it was possible that such mechanisms may have a role in the control of thyroid cell proliferation by TSH. Our findings that the TSH effect on proliferation may be completely reproduced by agents which specifically increase CAMP levels, does not support this hypothesis, at least in the case of the dog thyroid.…”

Section: Discussionmentioning

confidence: 99%

Stimulation by thyrotropin and cyclic AMP of the proliferation of quiescent canine thyroid cells cultured in a defined medium containing insulin

Roger¹,

Servais²,

Dumont³

1983

FEBS Letters

145

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We have developed serum-free primary cultures of differentiated follicular dog thyroid cells which allow the study of the hormonal control of cell proliferation. The cooperation of insulin and increasing cellular cyclic AMP by thyrotropin triggers the DNA synthesis and the proliferation. Dog thyroid cells are an example of a system in which cyclic AMP is a sufficient signal to stimulate the proliferation in quiescent cells. Thyroid

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Section: Discussionmentioning

confidence: 99%

Stimulation by thyrotropin and cyclic AMP of the proliferation of quiescent canine thyroid cells cultured in a defined medium containing insulin

Roger¹,

Servais²,

Dumont³

1983

FEBS Letters

145

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“…The plates were then flooded with a substrate of 2 g casein in 100 ml 0.1 M-citric acid, adjusted to pH 2.0, and incubated for 2.5 h at 37', after which the undigested protein was fixed with TCA solution containing 7.5 g/Ioo ml and stained -4th Amido Black. Samples of crystalline porcine pepsin (Ihch-Light Laboratories Ltd, Colnbrook, Bucks) and crystalline rennin, prepared in the laboratory by the method of Berridge & Woodward (1953), were run at the same time as the extracts. Much confusion exists in the literature concerning the identification and nomenclature of the different pepsins.…”

Section: Identijcation Of $Pubbit Stomach Proteasesmentioning

confidence: 99%

Comparison of the development of proteolytic activity in the abomasum of the preruminant calf with that in the stomach of the young rabbit and guinea-pig

Mj¹

1973

Br J Nutr

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1. Proteolytic activity was measured in the abomasal contents of five calves during the first 7 weeks of life and in the stomach contents of rabbits and guinea-pigs during the first 4 weeks of life.2. The pattern of protease secretion in the abomasum varied considerably among individual calves; in addition to rennin, some pepsin activity was found in most animals from the first sampling at 9 d of age.3. Only pepsin was secreted in the guinea-pig stomach from birth, at a consistently high level at all ages.4. The main peak of proteolytic activity in the rabbit stomach during the 1st week post partum had an optimum at pH 3·5–4·0, corresponding to that for calf rennin. During the 3rd week of life the main pepsin peak, with an optimum at pH 1·6–2·0, developed.5. Agarose gel electrophoresis of an extract of neonatal rabbit stomach mucosa showed the activity peak at pH 3·5–4·0 to be due to two slow-moving components of mobilities similar to that of crystalline rennin. At least one of these cross-reacted with antiserum to crystalline rennin.6. At 10 d and 3 weeks of age, activity at pH 1·6–2·0 was due to two faster-moving proteases, one being the main pepsin of the adult rabbit, which moved at the same speed as crystalline porcine pepsin, with the antiserum of which it cross-reacted.

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“…The crystalline rennin was made according to the method of Berridge & Woodward (2). The impurities were prepared as follows; the filtrate obtained after saturating commercial rennet with sodium chloride was acidified to pH 1-8.…”

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605. Preparation of a cheese with crystalline rennin

Berridge

1955

Journal of Dairy Research

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Kizer, Hankin, Speck & Aurand(i) have observed that the impurities associated with proteolytic enzymes are stimulating to lactic acid bacteria, and they have suggested that these substances may accelerate the ripening of dairy products. In view of these observations and suggestions an experiment begun in March 1954, on the preparation of cheese with crystalline rennin, is reported below. The results are in agreement with the suggestions of Kizer et al.Three 30 lb. Cheddar cheese were made from a single batch of milk. One control cheese was made with ordinary commercial rennet. The second cheese was made with crystalline rennin and the third with rennin plus impurities which are discarded during the preparation of crystalline rennin.The crystalline rennin was made according to the method of Berridge & Woodward (2). The impurities were prepared as follows; the filtrate obtained after saturating commercial rennet with sodium chloride was acidified to pH 1-8. A copious precipitate was formed. This precipitate was removed by filtration and stored in the refrigerator until needed. It had a low but definite activity, consequently when the amount of enzyme needed for 30 gal. of milk was calculated from the activity of the precipitate a much larger quantity of adventitious material than is present in commercial extracts accompanied the rennin. The crystalline enzyme was free from adventitious material.Parallel experiments indicate that the acid precipitate contained about 10% of the active enzyme present in the parent solution and about 80 % of the crude protein, making it about one-fifth of the specific activity of commercial rennet, on a dry-weight basis. The crystalline rennin had about ten times the specific activity of commercial extracts.Both crystals and precipitate were prepared for addition to the milk by dissolving in dilute phosphate buffer of pH 6*8.During making the control cheese behaved normally in every respect. The milk with crystalline rennin clotted very quickly (3 min.), but the curd remained soft for a relatively long time. In a small-scale parallel experiment similar curd was no firmer after half an hour than a curd produced by commercial rennet clotting in 9 min.The curd formed by crystalline rennin developed less acidity than the control; on applying the hot iron test threads only J in. long were formed in place of the normal 1 | in. threads. After pressing, the acidity, though sufficient, was less than that in the control, and the curd was softer.The curd formed with the preparation containing excess of adventitious material, when subjected to the hot iron test, formed a small number of threads which were both stouter and longer than normal.When the cheese were tasted after ripening for 4 months, the control was of normal pleasant flavour. The cheese made with adventitious material had a similar but stronger,

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516. A simple method for preparing crystalline rennin

Cited by 21 publications

References 4 publications

Stimulation by thyrotropin and cyclic AMP of the proliferation of quiescent canine thyroid cells cultured in a defined medium containing insulin

Stimulation by thyrotropin and cyclic AMP of the proliferation of quiescent canine thyroid cells cultured in a defined medium containing insulin

Comparison of the development of proteolytic activity in the abomasum of the preruminant calf with that in the stomach of the young rabbit and guinea-pig

605. Preparation of a cheese with crystalline rennin

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