Human collagenase: identification and characterization of an enzyme from rheumatoid synovium in culture

Synovial tissue from patients with rheumatoid arthritis produces lysis of gels of reconstituted collagen fibrils in culture and releases soluble collagenase when cultured in collagen-free medium. Collagen molecules in solution at neutral pH at 20 degrees and 27 degrees C are cleaved by the synovial enzyme into (3/4) and (1/4) length fragments. In this respect the action of synovial enzyme is similar to that of amphibian collagenase and distinct from that of bacterial collagenase. At 37 degrees C reconstituted collagen fibrils and native fibers are attacked by the enzyme and further degraded to polypeptides of low molecular weight. These polypeptides are produced only after denaturation of the larger fragments, which occurs at temperatures near 37 degrees C.     

罗非鱼胶原蛋白多肽果味饮料的生产工艺及稳定性研究

[目的]确定罗非鱼胶原蛋白多肽果味饮料的最佳生产工艺。[方法]利用罗非鱼鱼鳞制成的胶原蛋白以及菠萝果汁为原材料,通过单因素度试验和正交试验来确定果味饮料的最佳配方和条件。[结果]罗非鱼胶原蛋白多肽果味饮料的最佳生产配方为菠萝果汁40%,蔗糖5%,有机酸0.4%,胶原蛋白5%;最佳稳定剂为黄原胶0.02%,单甘脂0.12%,海藻酸钠0.15%,阿拉伯胶0.10%;最佳均质压力为25 MPa;最佳杀菌温度为115℃时间为15 min。[结论]用罗非鱼鱼鳞和菠萝为原料制作的果味饮料营养丰富,稳定性好,生产工艺操作简单,具有较高的工业生产应用价值。     

Collagen: mobile water content of frozen fibers

From the change in the nuclear magnetic resonance splitting of heavy water in oriented wet collagen fibers at low temperatures, it is estimated that about 0.6 gram of heavy water per gram of collagen does not freeze. This estimate has been confirmed by a measurement of the heat evolved on melting "frozen" wet collagen. The water that does not freeze retains liquid-like mobility even at temperatures as low as -50 degrees C.     

鱼鳞胶原蛋白干燥技术研究

鱼鳞中提取的胶原蛋白具有广泛的应用,其制备过程对产品的质量影响较大,而胶原蛋白的干燥工艺也备受关注。探讨了现有的胶原蛋白的干燥技术,并对该技术的发展进行展望。     

东北林蛙皮中胶原蛋白含量的测定及提取工艺

为了充分利用东北林蛙资源,利用羟脯氨酸法对废弃的林蛙皮肤进行了胶原蛋白的提取试验,测定了林蛙皮肤中总胶原蛋白的含量,并对提取方法进行了优化。酸、酶提取对比试验表明:加入胃蛋白酶后提取率明显提高;通过酶的正交试验,确定出最佳提取条件为37℃、72h、30mg胃蛋白酶;以最佳条件提取胶原蛋白,并经盐析、透析和真空冷冻干燥,得到海绵状的胶原蛋白产品,含量检测表明成品的收率为15%,纯度为54.1%。     

HACCP在罗非鱼鱼鳞胶原蛋白多肽生产中的应用

[目的]将HACCP体系应用于罗非鱼鱼鳞胶原蛋白多肽的生产过程中,确保工业生产罗非鱼鱼鳞胶原蛋白多肽的安全性。[方法]阐述了胶原蛋白多肽的生产工艺流程,分析了各环节的潜在危害,并设定了关键限值、监控频率与措施、纠偏措施、档案记录和验证程序来监控关键点。[结果]确定原料验收、酶解提取、浓缩、喷雾干燥、磁选和内包装为关键控制点,并制定了HACCP计划表,从而在罗非鱼鱼鳞胶原蛋白生产中建立了质量安全控制体系。[结论]HACCP体系的实施降低了罗非鱼鱼鳞胶原蛋白生产中的危险因素,保障了胶原蛋白多肽的品质和食用安全。     

Gelatin: a poor substrate for a mammalian collegenase

A rabbit tumor collagenase was purified more than 5000-fold. In this form it degrades native collagen in helical conformation at 37 degrees C, pH 7.6, into two fragments, but it had little capacity to cleave gelatin, an indication of the importance of higher-order structure of substrate for this enzyme in pure form. It is likely that, in vivo, enzymes other than collagenase degrade gelatin polypeptides produced by primary collagenolysis.     

Cooperative critical thermal transition of potassium accumulation in smooth muscle

The steady-state levels of potassium and sodium of taenia coli of guinea are critically affected by varying temperature in the narrow range 12 degrees to degrees C. For the accumulation of both cations the critical temperature, T(c), is 13.8 degrees C the presence of millimolar external potassium. The value of T(c), decreases 10.0 degrees C when the external potassium is raised to 10 millimolar. Since, at a fixed Temperature, the potassium accumulation follows a cooperative mechanism, the results are compared with the quantitative predictions of this approach. The itical thermal transition behavior can be described in terms of the cooperative cumulation process.     

Temperature-sensitive pawns: conditional behavioral mutants of Paramecium aurelia

"Pawns" are mutants of Paramecium aurelia in which the process of calcium activation during membrane excitation is genetically impaired, with a corresponding loss of avoiding reactions. Mutants are selected that behave normally when grown at 23 degrees C but as pawns at 35 degrees C. The normal excitation can now be disrupted and restored in the same strain at will.     

Aminoguanidine prevents diabetes-induced arterial wall protein cross-linking

Age-associated increases in collagen cross-linking and accumulation of advanced glycosylation products are both accelerated by diabetes, suggesting that glucose-derived cross-link formation may contribute to the development of chronic diabetic complications as well as certain physical changes of aging. Aminoguanidine, a nucleophilic hydrazine compound, prevented both the formation of fluorescent advanced nonenzymatic glycosylation products and the formation of glucose-derived collagen cross-links in vitro. Aminoguanidine administration to rats was equally effective in preventing diabetes-induced formation of fluorescent advanced nonenzymatic glycosylation products and cross-linking of arterial wall connective tissue protein in vivo. The identification of aminoguanidine as an inhibitor of advanced nonenzymatic glycosylation product formation now makes possible precise experimental definition of the pathogenetic significance of this process and suggests a potential clinical role for aminoguanidine in the future treatment of chronic diabetic complications.     

胶原蛋白在食品和化妆品中的应用

近年来,随着胶原提取技术的发展以及对胶原蛋白与胶原多肽的功能性质认识的提高,胶原蛋白的研究与应用成为一个新的热点。结合胶原蛋白的结构和特性,综述了胶原蛋白在功能性食品、肉制品改良剂、食品包装材料、食品涂层材料等食品工业领域的广泛应用以及胶原蛋白在化妆品中的功效与应用,并对胶原蛋白的研究方向进行了预测。     

Oxidative autoactivation of latent collagenase by human neutrophils

The pathological destruction of collagen plays a key role in the development of inflammatory disease states affecting every organ system in the human body. Neutrophils localized at inflammatory sites can potentially degrade collagen by releasing a metalloenzyme, collagenase, which is stored in a latent inactive form. Triggered human neutrophils were shown to release and simultaneously activate their latent collagenase. The activation of the latent enzyme was coupled to an oxidative process that required the generation of a highly reactive oxygen metabolite, hypochlorous acid. Oxidative regulation of latent collagenase activity may be important in the pathogenesis of connective tissue damage in vivo.     

Kinetics of the fe2+-mg, order-disorder reaction in anthophyllites: quantitative cooling rates

The kinetics of the Fe(2+)-Mg, order-disorder phenomenon in a highly ordered natural anthophyllite have been determined over the temperature range from 400 degrees to 720 degrees C at a pressure of 2 kilobars. At temperatures of 600 degrees C and above, equilibrium is attained by disordering as well as ordering reactions. The intracrystalline exchange is defined by a standard Gibbs free energy of 4247 +/- 54 calories per formula unit. Rate studies at 550 degrees and 500 degrees C show that equilibrium is attained by ordering but not by disordering within the same time scale and that the exchange reaction is characterized by an activation energy of approximately 55 kilocalories per formula unit. An equilibration temperature for the natural anthophyllite of 270 degrees C is determined from the termination of the ordering process owing to excessively slow reaction kinetics after approximately 10(7) years. From the rate constants of the exchange process, for different crystallization temperatures, the apparent equilibration temperature of 270 degrees C defines a maximum linear cooling rate for the rock of 1 x 10(4) degrees C per year.     

甘氨酸、脯氨酸及羟脯氨酸介导胶原蛋白代谢研究进展

氨基酸不仅是胶原蛋白合成的底物,而且可以作为信号分子参与胶原蛋白代谢的调控。文章从胶原蛋白合成和分解代谢角度对胶原蛋白代谢的营养调控研究进行综述,重点梳理了甘氨酸（glycine,Gly）、脯氨酸（proline,Pro）和羟脯氨酸（hydroxyproline,Hyp）对胶原蛋白代谢的影响,及其介导胶原蛋白代谢的潜在信号通路和分子机制,并对未来的研究方向进行了展望。     

Collagen defect induced by penicillamine

Collagen synthesis, as judged by the accumulation of collagen in a subcutaneous, induced granuloma, was significantly decreased by penicillamine. Penicillamine also caused a marked increase in the amount of soluble collagen in skin and a sharp drop in insoluble material. These findings, which reflect an abnormal pattern of collagen metdbolism, are accompanied by an inhibition of wound-healing and by skin fragility.     

Adenosine 3',5'-monophosphate modulates thyrotropin receptor clustering and thyrotropin activity in culture

A biologically active rhodamine conjugate of thyrotropin binds at 4 degrees C to diffusely distributed membrane thyrotropin receptors which patch and become endocytosed into thyroid cells in a temperature-sensitive process. When the cells are first incubated with 8-bromo-cyclic adenosine monophosphate at 37 degrees C, the conjugate also binds to clustered receptors at 4 degrees C. Furthermore, 8-bromo-cyclic adenosine monophosphate reduces the amount of adenosine 3',5'-monophosphate (cyclic AMP) induced by thyrotropin. Hence, increased intracellular cyclic AMP induces receptor patching and reduces the concentration of cyclic AMP normally induced by thyrotropin. This suggests that cyclic AMP acts both as the second messenger of thyrotropin and also as the regulator of the level of thyrotropin receptors.     

加热温度及时间对牛肉胶原蛋白特性及嫩度的影响

 【目的】通过研究不同加热温度和加热时间来探究胶原蛋白特性对嫩度的影响,为中国高熟度牛肉嫩度特性研究提供参考。【方法】将牛半腱肌肉在60、70、80、90和100℃水浴温度下分别加热30、60、90、120和150 min,通过测定剪切力、蒸煮损失、水分含量、质构特性、结缔组织机械强度、胶原蛋白含量及热溶解性、胶原蛋白共价交联以及扫描电镜等指标探究嫩度的变化规律,通过相关性分析得出影响嫩度的关键因素。【结果】随着加热温度的升高和加热时间的延长,牛半腱肌肉剪切力降低,蒸煮损失增大,水分含量降低;总胶原蛋白和不溶性胶原蛋白随着加热温度的升高其相对含量明显增加,随着加热时间的延长其相对含量变化不显著,可溶性胶原蛋白含量及热溶解性增加、羟赖氨酸吡啶啉（HP）相对含量上升、赖氨酸吡啶啉（LP）相对含量下降,黏着性增大,胶黏性、咀嚼性、凝聚性和回弹性减小。随着加热时间的延长,牛肉剪切力与蒸煮损失呈显著负相关（P＜0.05）;与水分含量、硬度、凝聚性、胶黏性、咀嚼性以及回弹性呈极显著正相关（P＜0.01）;与总胶原蛋白、可溶性胶原蛋白、不溶性胶原蛋白含量、胶原蛋白热溶解性以及羟赖氨酸吡啶啉含量呈极显著负相关（P＜0.01）。总胶原蛋白、不溶性胶原蛋白的含量与蒸煮损失呈极显著正相关（P＜0.01）;羟赖氨酸吡啶啉与肌肉的黏着性和总胶原蛋白含量呈极显著正相关（P＜0.01）,与弹性、可溶性胶原蛋白以及不溶性胶原蛋白含量呈显著正相关（P＜0.05）,与胶黏性和咀嚼性呈显著负相关（P＜0.05）,赖氨酸吡啶林与弹性呈显著负相关（P＜0.05）,与凝聚性呈显著正相关（P＜0.05）,与回弹性呈极显著正相关（P＜0.01）。与加热温度相比,加热时间对牛肉嫩度的影响更为显著。牛肉嫩度与胶原蛋白含量及热溶解性、HP、蒸煮损失、水分含量、硬度、凝聚性、胶黏性、回弹性和咀嚼性有关;胶原蛋白含量及热溶解性与蒸煮损失和水分含量有关。肌肉的黏着性、弹性、回弹性、凝聚性、胶黏性和咀嚼性等均与共价交联有关,胶原蛋白热溶解性与共价交联无关。【结论】高熟度牛肉的食用品质很大程度上取决于加热时长与胶原蛋白特性,胶原蛋白特性对嫩度的影响随着加热时间的延长而增加。胶原蛋白含量与热溶解性以及共价交联量通过影响肉的质构特性来改善嫩度。随着加热时间的延长,胶原蛋白和共价交联相对含量增加,结缔组织强度增加从而削弱了肌纤维对嫩度的影响,使嫩度得到改善。     

Oxygen isotope fractionation in the system dolomite-calcite-carbon dioxide

Oxygen isotopes were equilibrated between carbon dioxide and calcite at four temperatures in the range 350 degrees to 610 degrees C and between carbon dioxide and dolomite at 350 degrees and 400 degrees C. Carbon of unusual isotopic composition was used as a tracer to demonstrate the nature and extent of the exchange process. Extrapolation of these data at lower temperatures indicates that at 25 degrees C dolomite is enriched in oxygen-18 by 6.8 per mil with respect to calcite. This result indicates that those natural dolomite-calcite assemblages which show very small fractionations were not formed in isotopic equilibrium.     

Bacterial Sulfate Reduction Above 100{degrees}C in Deep-Sea Hydrothermal Vent Sediments

The currently known upper temperature limit for growth of organisms, shared by a number of archaebacteria, is 110 degrees C. However, among the sulfate-reducing bacteria, growth temperatures of greater than 100 degrees C have not been found. A search for high-temperature activity of sulfate-reducing bacteria was done in hot deep-sea sediments at the hydrothermal vents of the Guaymas Basin tectonic spreading center in the Gulf of California. Radiotracer studies revealed that sulfate reduction can occur at temperatures up to 110 degrees C, with an optimum rate at 103 degrees to 106 degrees C. This observation expands the upper temperature limit of this process in deep-ocean sediments by 20 degrees C and indicates the existence of an unknown group of hyperthermophilic bacteria with a potential importance for the biogeochemistry of sulfur above 100 degrees C.     

Geothermal System at 21{degrees}N, East Pacific Rise: Physical Limits on Geothermal Fluid and Role of Adiabatic Expansion

Pressure-volume-temperature relations for water at the depth of the magma chamber at 21 degrees N on the East Pacific Rise suggest that the maximum subsurface temperature of the geothermal fluid is about 420 degrees C. Both the chemistry of the discharging fluid and thermal balance considerations indicate that the effective water/rock ratios in the geothermal system are between 7 and 16. Such low ratios preclude effective metal transport at temperatures below 350 degrees C, but metal solubilization at 400 degrees C and above is effective even at such low ratios. It is proposed that the 420 degrees C fluid ascends essentially adiabatically and in the process expands, cools, and precipitates metal sulfides within the upper few hundred meters of the sea floor and on the sea floor itself.