Characteristics and use of protein hydrolysates (review)

Properties of protein hydrolysates and possible uses of these substances in research and various branches of industry are considered. The main problem discussed in this paper is the relationship between the degree of protein conversion and characteristics (structural-functional and physicochemical) of hydrolysates.     

Isolation of protein hydrolysates with given properties (a review)

Methods for obtaining protein hydrolysates with certain given properties are considered. It is shown that, besides food proteins, various yeast proteins can be used. Advantages and disadvantages of different types of hydrolysis, hydrolysis conditions, methods of hydrolysate purification and prevention of labile amino acid destruction are described.     

General review of fish protein hydrolysates

Fish protein hydrolysates are generally considered to be the liquefied products obtained from fish by the action of proteolytic enzymes under accelerated conditions of digestion. The proteolytic enzymes which are used for the digestion of fish proteins must be active either above the survival temperature of spoilage bacteria or outside the range of pH which would support their growth. By suitable selection of proteolytic enzymes and conditions for hydrolysis some control over the digestion can be achieved to give a range of products. This paper reviews the work done here and elsewhere on fish protein hydrolysates and discusses their potential for making more effective use of the fish resources.     

Properties and uses of protein hydrolysates (Review)

Properties of protein hydrolysates and possible uses of these substances in research and various branches of industry are considered. The main problem discussed in this paper is the relationship between the degree of protein conversion and characteristics (structural-functional and physicochemical) of hydrolysates.     

Production of polyhydroxybutyrate by Ralstonia eutropha from protein hydrolysates

Polyhydroxybutyrate (PHB) was produced by Ralstonia eutropha DSM 11348 (formerly Alicaligenes eutrophus) in media containing 20–30 g l⁻¹ casein peptone or casamino acids as sole sources of nitrogen. In fermentations using media based on casein peptone, permanent growth up to a cell dry mass of 65 g l⁻¹ was observed. PHB accumulated in cells up to 60%–80% of dry weight. The lowest yields were found in media without any trace elements or with casamino acids added only. The residual cell dry masses were limited to 10–15 g l⁻¹ and did not contain PHB. The highest productivity amounted to 1.2 g PHB l⁻¹ h⁻¹. The mean molecular mass of the biopolymer was determined as 750 kDa. The proportion of polyhydroxyvalerate was less than 0.2% in PHB. The bioprocess was scaled up to a 300-l plant. During a fermentation time of 39 h the cells accumulated PHB to 78% w/w. The productivity was 0.98 g PHB l⁻¹ h¹. Received: 8 July 1998 / Accepted: 26 August 1998     

Production and purification of urokinase: a comprehensive review

An increased emphasis on prevention of fatalities due to thrombovascular disorders is broadening opportunities for several cardiovascular agents, especially plasminogen activators, for preventing strokes and heart attacks. Hence, urokinase, as one of the most potent plasminogen activators is attracting a great deal of attention. Developments in cell lines and bioprocess technology have made it possible to produce urokinase from in vitro cell culture. Attempts are now underway to enhance urokinase production from cell culture through media manipulation, bioreactor cultivation, and innovative purification techniques. Downstream processing also poses an intricate problem due to the complexity of cell culture extracts, susceptibility of urokinase to autocatalytic and proteolytic degradation and due to the presence of plasminogen activator inhibitors in the culture media. Hence, enhancing cellular productivity and downstream product recovery continue to be major challenges as discussed in this review. Furthermore, an approach for integrated upstream and downstream processing is needed to develop an economically viable technology. In the present review the emerging trends in urokinase production and purification have been discussed in detail.     

Preparative parallel protein purification (P4)

In state of the art drug discovery, it is essential to gain structural information of pharmacologically relevant proteins. Increasing the output of novel protein structures requires improved preparative methods for high throughput (HT) protein purification. Currently, most HT platforms are limited to small-scale and available technology for increasing throughput at larger scales is scarce. We have adapted a 10-channel parallel flash chromatography system for protein purification applications. The system enables us to perform 10 different purifications in parallel with individual gradients and UV monitoring. Typical protein purification applications were set up. Methods for ion exchange chromatography were developed for different sample proteins and columns. Affinity chromatography was optimized for His-tagged proteins using metal chelating media and buffer exchange by gel filtration was also tested. The results from the present system were comparable, with respect to resolution and reproducibility, with those from control experiments on an AKTA purifier system. Finally, lysates from 10 E. coli cultures expressing different His-tagged proteins were subjected to a three-step parallel purification procedure, combining the above-mentioned procedures. Nine proteins were successfully purified whereas one failed probably due to lack of expression.     

Preparation of fish protein hydrolysates

A process for the preparation of fish protein hydrolysates using commercially available proteolytic enzymes is described. Both non-fatty and fatty species of fish have been used as the raw material and the hydrolysates obtained have been assessed in nutritional studies on neonatal animals. Data on the release of nitrogenous substances during the digestion of cod with the enzyme papain are presented, together with amino acid analyses of the various fractions produced. As far as hydrolysates from non-fatty species are concerned there are no technical difficulties in preparing a spray-dried or concentrated product suitable for animal feeding. For hydrolysates from fatty species, however, it is necessary either to remove the oil mechanically or to stabilise it with suitable antioxidants. For the present exercise, hydrolysates were frozen and stored at ?30°C until required for the nutritional studies. Before any industrial development is considered, further studies on the drying and storing of hydrolysates from fatty species are necessary.     

Biological methods of air purification (review of the literature)

Biological methods of air purification are reviewed, which can be applied to deep air purification of complex multicomponent mixtures from harmful, toxic and odorous substances at room temperature and atmospheric pressure. Microbiological and technological aspects of the problem are discussed. Operation characteristics of biofilters, bioscrubbers and trickle bed bioreactors are compared. Prospects of air biopurification are considered.     

Production and purification of monoclonal T lymphocyte antigen binding molecules (TABM)

The thyroid hormone derivative N-bromoacetyl-3,3',5-triiodothyronine (BrAcT3) acts as an active site-directed inhibitor of rat liver iodothyronine deiodinase. Lineweaver Burk analysis of enzyme kinetic measurements showed that BrAcT3 is a competitive inhibitor of the 5'-deiodination of 3,3',5'-triiodothyronine (rT3) with an apparent Ki value of 0.1 nM. Preincubations of enzyme with BrAcT3 indicated that inhibition by this compound is irreversible. The inactivation rate obeyed saturation kinetics with a limiting inactivation rate constant of 0.35 min-1. Substrates and substrate analogs protected against inactivation by BrAcT3. Covalent incorporation of 125I-labeled BrAcT3 into "substrate-protectable" sites was proportional to the loss of deiodinase activity. The results suggest that BrAcT3 is a very useful affinity label for rat liver iodothyronine deiodinase.     

Enzymatic debittering of food protein hydrolysates

Protein hydrolysates have a range of applications in the food and allied healthcare sectors. Bitterness is a negative attribute associated with most food protein hydrolysates. The development of biotechnological solutions for hydrolysate debittering is ongoing. Specific enzymatic debittering strategies have focused on the application of proline specific exo- and endopeptidases given the contribution of proline residues to peptide/hydrolysate bitterness. Hydrolysate manufacturing conditions may also play an important role in bitterness development. Practical solutions to hydrolysate debittering are likely to involve judicious choice of enzymatic processing conditions in conjunction with the use of peptidase activities having targeted hydrolytic specificity.     

Production and purification of an untagged recombinant pneumococcal surface protein A (PspA4Pro) with high-purity and low endotoxin content

Applied Microbiology and Biotechnology - Streptococcus pneumoniae is the main cause of pneumonia, meningitis, and other conditions that kill thousands of children every year worldwide. The...     

Production and purification of recombinant DP1B silk-like protein in plants

Spider dragline silk of Nephila clavipes consists of two highly repetitive proteins, spidroin 1 and spidroin 2. To develop a plant platform for production of recombinant silk-like protein, two plant-optimized DP1B genes were synthesized to mimic spidroin 1. DP1B-8P encodes for a 64 kD DP1B silk-like protein and DP1B-16P for a 127 kD DP1B silk-like protein. Both genes have been introduced into Arabidopsis for leaf-based production driven by the 35S promoter and for seed-specific production driven by the -conglycinin subunit promoter, respectively. They have also been expressed in somatic soybean embryos under the control of the -conglycinin subunit promoter. The results demonstrate the synthesis and accumulation of DP1B silk-like protein in leaves and seeds of Arabidopsis, as well as in somatic soybean embryos. They suggest that seeds are the more preferred tissue for DP1B production since they offer higher production yield and quality. In addition, a simplified protocol for purifying DP1B from plant tissue is discussed.