Enzyme immobilization is the core technology of biocatalysis. Over the past few decades, enzyme immobilization research mainly focused on single enzyme immobilization. In recent years, multi-enzyme immobilization attracts more and more attention as it could increase the local concentration of reaction and improve the reaction yield. In this review, a summary of the recent progress, together with our research, is presented. Special emphasis is placed on four methods in multi-enzymes co-immobilization, namely, the nonspecific covalent co-immobilization, the nonspecific non-covalent co-immobilization, the non-covalent encapsulation co-immobilized and the site specificity co-immobilized. Finally, some industrial uses of immobilized multi-enzymes were addressed and the application prospect of multi-enzyme immobilization was highlighted.
Biocatalysis ; Enzymes, Immobilized

Three methods C2, 3-diaminonaphathalene molecular fluorimetry, hydride generation atomic fluorescence spectrometry (HG-AFS) and hydride generation atomic absorption spectrometry (HG-AAS)] for the determination of selenium in food samples were compared with one another. The absolute detection limits of HG-AFS and HG-AAS are 1.2 and 0.9ng respectively, lower than that of molecular fluorimetry(3.9ng). The precisions and accuracies of HG-AFS and HG-AAS are similar to molecular fluorimetry. When these methods were used to determine selenium in 6 standard reference materials, there was no significant difference among the mean values from each of the methods.

This paper described a microprocedure for the simultaneous determination of retinol (Vitamin A), alpha and gamma tocopherol (Vitamin E) in plasma by high performance liquid chromatography. A reversed-phase C18 column with precolumn was used. The mobile phase was water in methanol (2:98) and the flow rate was 1.8ml/min. An ultraviolet detector with 300 nm was used. The chromatogram was completed in 12 min and the retinol, alpha and gamma tocopherol were quantitated by the peak area ratio and weight ratio using benzo (e) pyrene as an internal standard. The mean recovery of retinol and alpha tocopherol were 93.9% and 106.9% respectively. The coefficient of variation (CV%) were 5.2 for retinol, 4.8 for gamma tocopherol and 6.3 for alpha tocopherol. In order to assess the possibility of measuring pooled samples instead of individual samples, the value of individuals was compared with the value of the pooled sample. The results showed that the pool values and the mean ? SD of the 25 individuals compared very favourably.6500 blood samples were collected from both sexes and 130 communities of 65 counties. The plasma retinol and tocopherols were analyzed. The average plasma retinol value (X?SD,?g/dl) was 52 ?9.2 for male and 41 ?6.8 for female. The average plasma alpha tocopherol value (X?SD) was 703?108 for male and 735?101 for female. The mean ? SD (?g/dl) of total vitamin E were 750 ? 124 and 776 ?104 respectively for male and female.

Many factors influence the elastin-like polypeptides (ELPs) self-assembled into micron-sized particles. However, few efforts were made to investigate these factors. Using the ELPs [KV8F]n as the target, we studied systematically the factors with the dynamic light scattering. Our results show that the particle size increased and the uniform of particles decreased with the increase of the molecular weight. The analysis of size variation in self-assembled ELPs in response to changes in salt concentration indicated that the size increased with increasing the salt concentration, and the opposite response was observed when the concentration was above 0.4 mol/L. Under these conditions, the particles are micron-sized and larger than 1.1 μm. However, when the fusions containing the same ELPs and xylanase or 1,3-propanediol oxidoreductase, the size of the self-assembled ELPs particles decreased dramatically, which was only about 1/10 of that of the free ELPs. We proposed that the solvent accessible charged area of the enzymes could interact with the ELPs, the sterical hindrance of the enzymes prevent the aggregation of the ELPs. This might be the most important parameter in altering the particle size sharply.
Elastin ; chemistry ; Molecular Weight ; Particle Size ; Peptides ; chemistry ; Salts ; chemistry

Objective Reninoma is a rare benign tumor of the renal juxtaglomerular cell apparatus that causes hypertension and hypokalemia via hypersecretion of renin,while it is extremely rare that reninoma induced hypertensive crisis with reversible posterior encephalopathy syndrome (RPES).To improve the clinical understanding for this disease,we conducted a case-analysis.Methods To analyze the clinical and pathological data of a case of reninoma-induced hypertensive crisis with reversible posterior encephalopathy syndrome,who was admitted to Peking University First Hospital in November,2007 and follow-up.Results This was a 16-year old female patient,onset with suddenly spasm with loss of consciousness,while blood pressure stepped up to 210/140 mm Hg( 1 mm Hg =0.133 kPa),and the head magnetic resonance imaging (MRI) revealed “multiple long-T2 signal”,and hypopotassaemia(2.8-3.2 mmol/L),urine protein positive,ultrasoundcardiogram revealed left ventricular hypertrophy,laboratory study revealed hyperreninism (38.23ng · ml-1 · h-1,normal range 0.07-1.15 ng· ml-1 · h-1 ) and hyperaldosteronism(660.9 ng/L,normal range 60-174 ng/L),abdominal CT-Scan revealed a mass at right kidney,blood pressure achieved safety range and the head MRI was rechecked and revealed “the abnormal long-T2 signal disappeared”.The clinical diagnosis was reninoma induced hypertensive crisis with RPES.The tumor was resected and the pathologic diagnosis was reninoma.The patient remained normotensive in the postoperative period without any medication.Conclusions Reninoma represents a rare but surgically curable cause of hypertension,thus the clinical suspicion of it is very important in young patients.If the diagnosis is confirmed,positive treatment must be done immediately to improve the prognosis.The most common cause of RPES is hypertension,and the diagnosis depends on the distinctive head MRI.There is always a good prognosis with the decline of blood pressure rapidly.

Dietary fiber contents in 34 common foods perchased in Beijing markets have been determined with detergent method, including neutral detergent fiber, acid detergent fiber, cellulose, hemicellulose and lignin. On dry basis, the dietary fiber contents of vegetables varied with kinds of food: the dietary fiber contents were higher in tender stems, leaves, stalks and flowers; lower in starchy tubers and roots; medium in non-starchy tubers and roots. The propotions of dietary fiber components were different in various categories of foods. Cellulose was the major component in vegetables and legumes, but in most cereals, hemicellulose content was higher than cellulose. All foods had the lowest lignin content with the exception of garlic bolt.

Gitelman's syndrome (GS) is an autosomal recessive hereditary tubulopathy.It is caused by sodium reabsorption in the distal convoluted tubule of the renal unit,which is not yet fully cured.It is characterized by great heterogeneity with clinical manifestations.Some patients with no symptoms,were confirmed by hypokalemia with physical examination.The others can be manifested as fatigue,nocturia,polydipsia and hypotension.Less literature is reported about GS combined with osteoarthrosis.In this report,the author reported a patient of GS with osteoarthrosis characterized by hypokalemia,hypomagnesemia,metabolic alkalosis,lower blood pressure,and swelling and pain in left knee joint.The symptoms were improved after treatment with potassium and magnesium supplementation

A modification of Watkinson's method was used for the flaorimetric determination of selenium in blood, hair, urine and animal tissues with 2,3-Di-aminonaphthalene. A mixture of sulphuric, perchloric acid and sodium molybdate was used for digestion. As little as 3 ng selenium in the sample could be estimated out. Coefficients of variation and recoveries for blood, hair, urine and animal tissues were 3.9, 5.5, 3.3 and 5.6%, and 97.0, 95.0, 97.8 and 99.8% respectively. No significant difference in selenium content estimated was found as graded amounts of samples were taken for analysis, indicating no foreign interference in the extracts. Both precision and accuracy of this method are satisfactory.

2,3-Diaminonaphthalene was used for the fluorometric determination of selenium in cereals and vegetables. Nitric-perchloric-sulphuric acids mixture was used for digestion. Coefficient of variation and recovery for cereals were 4-10% and 97.1%, and for vegetables were 4-18% and 97.8% respectively. Addition of hydrochloric acid to the final digests could be omitted for ordinary cereals and soybean, but it was necessary for samples from seleni-ferous area and some vegetables with higher selenium content such as mushrooms.