Pyrimidine-Purine and Pyrimidine Heterodinucleosides Synthesis Containing a Triazole Linkage

This article describes a synthetic route to generate two purine-pyrimidine and pyrimidine heterodinucleosides. Both microwave activated regioselective alkylation using hydride and copper-catalyzed-azide-alkyne-cycloaddition (CuAAC) were used in order to perform the synthesis.     

Novel Method for the Covalent Immobilization of Oligonucleotides via Diels-Alder Bioconjugation

Abstract

The synthesis of cyclohexadiene and maleimide derivatives and their use for the functionalization of oligonucleotides and the coating of glass surfaces is reported. A method for the covalent attachment of diene or maleimide modified oligonucleotides to the coated glass surfaces via aqueous Diels-Alder reactions is presented.     

New Solid Supports Linking Nucleoside Scaffolds

Abstract

An easy and efficient strategy to obtain new nucleoside based solid supports in which the nucleoside moieties have been anchored to the solid support through the nucleobase is here proposed. A simple and efficient solid-phase synthesis of 5′ and 3′-derivatized uridine analogues has so been developed, following methodologies well established in organic chemistry.     

Solid Phase Synthesis of Phosphorothioate Oligonucleotides Utilizing Diethyldithiocarbonate Disulfide (DDD) as an Efficient Sulfur Transfer Reagent

Abstract

Diethyldithiodicarbonate (DDD), a cheap and easily prepared compound, is found to be a rapid and efficient sulfurizing reagent in solid phase synthesis of phosphorothioate oligodeoxyribonucleotides via the phosphoramidite approach. Product yield and quality based on IP-LC-MS compares well with high quality oligonucleotides synthesized using phenylacetyl disulfide (PADS) which is being used for manufacture of our antisense drugs.      

The 6-Methoxymethyl Derivative Of Pyrrolo-Dc For Selective Fluorometric Detection Of Guanosine-Containing Sequences

The β-cyanoethyl phosphosphoramidite derivatives of 6-methyl- and 6-methoxymethyl-3-(2-deoxy-β-D-ribofuranosyl)-3H-pyrrolo[2,3-d]pyrimidin-2-one have been synthesized. These monomers have been employed for oligodeoxynucleotide synthesis to evaluate their effect on duplex stability and ability to fluorometrically report on hybridization. The structurally conservative 6-methoxymethyl-substitution results in a pyrrolocytidine that is stabilizing toward hybrid formation (Δ Tm = +1.3 °C) whereas the known 6-methylpyrrolocytidine is destabilizing (Δ Tm = ?4.7 °C), in the sequence examined. The 6-methoxymethylpyrrolocytidine retains excellent mismatch discrimination and its fluorescence is selectively quenched when hybridized to a match oligodeoxynucleotide sequence. The quenching of fluorescence for an internal position is approximately three-fold, whereas a terminal position (5′-end or 3′-end) experienced approximately two-fold decrease in the fluorescence intensity.     

Candida rugosa脂肪酶同工酶的分离及选择固定化

采用“界面亲和层析”,从商品Candida rugosa脂肪酶（CRL）中分离到三个同工酶（CRL-1、CRL-2和CRL-3）,它们在水-有机溶剂双液相体系中催化(R,S)-萘普生甲酯的不对称水解反应,具有不同的立体选择性.分析表明：CRL-1和CRL-2上不同程度地非共价结合有小分子的酸性化合物,阻碍了其活性位点处疏水腔的完全开放;CRL-3上不含有该小分子酸性化合物,活性位点处疏水腔可处于完全开放构象.据此分别将CRL同工酶选择性地固定在不同的载体(GDX101和YWG-NH₂)上.通过简单易行的选择吸附步骤,可同时达到同工酶的分离及固定化目的,提出了一种对结构上相差不大同工酶分离的便利方法.     

Enhanced protein stability through minimally invasive,direct, covalent,and site‐specific immobilization

Bioconjugating protein to nonbiological surfaces is an essential component of many promising biotechnologies impacting diverse applications such as medical diagnostics, biocatalysis, biohazard detection, and proteomics. However, to enable the widespread economical use of immobilized‐protein technologies, long‐term stability, and reusability is essential. To enhance protein stability in harsh conditions, herein we report a minimally invasive and covalent bioconjugation that enables precise control of the immobilization location at potentially any surface‐accessible location where the incorporated unnatural amino acid does not impact protein structure and function. Specifically, the PRECISE system is introduced where a uniquely reactive unnatural amino acid was incorporated site‐specifically at a prespecified location in GFP using cell‐free protein synthesis. The GFP was then directly and covalently attached to superparamagnetic beads by the unnatural amino acid in a single click reaction. The immobilized GFP was probed for retained activity and stability under harsh conditions including freeze‐thaw cycling and incubation in urea at elevated temperatures. The immobilized GFP was more stable compared to unattached protein in all cases and for all durations observed. The enhanced stability of the immobilized protein is a promising step towards long‐term protein stability for biocatalysis and other immobilized‐protein applications. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2013     

环糊精葡萄糖基转移酶的性质、应用与固定化研究进展

本文总结了环糊精葡萄糖基转移酶的性质、应用与固定化研究的进展情况,引用文献４７篇。     

The Immobilization Antigen of Paramecium aurelia is a Single Polypeptide Chain

The immobilization antigen (i-antigen) fraction of Paramecium aurelia syngen 4 is shown to contain a protease that is activated by mercaptoethanol. After the protease has been heat-inactivated, the molecular weight of the i-antigen (∼250,000 daltons) cannot be decreased by mercaptoethanol treatment. It is demonstrated that the i-antigen is a single polypeptide chain. Reasons are also given why low molecular weight subunits were previously reported by other authors.     

The Impact of COVID-19 On Comorbidities: A Review Of Recent Updates For Combating It

Coronavirus disease is caused by the SARS-CoV-2 virus. The virus first appeared in Wuhan (China) in December 2019 and has spread globally. Till now, it affected 269 million people with 5.3 million deaths in 224 countries and territories. With the emergence of variants like Omicron, the COVID-19 cases grew exponentially, with thousands of deaths. The general symptoms of COVID-19 include fever, sore throat, cough, lung infections, and, in severe cases, acute respiratory distress syndrome, sepsis, and death. SARS-CoV-2 predominantly affects the lung, but it can also affect other organs such as the brain, heart, and gastrointestinal system. It is observed that 75 % of hospitalized COVID-19 patients have at least one COVID-19 associated comorbidity. The most common reported comorbidities are hypertension, NDs, diabetes, cancer, endothelial dysfunction, and CVDs. Moreover, older and pre-existing polypharmacy patients have worsened COVID-19 associated complications. SARS-CoV-2 also results in the hypercoagulability issues like gangrene, stroke, pulmonary embolism, and other associated complications. This review aims to provide the latest information on the impact of the COVID-19 on pre-existing comorbidities such as CVDs, NDs, COPD, and other complications. This review will help us to understand the current scenario of COVID-19 and comorbidities; thus, it will play an important role in the management and decision-making efforts to tackle such complications.     

Heterofunctional Magnetic Metal‐Chelate‐Epoxy Supports for the Purification and Covalent Immobilization of Benzoylformate Decarboxylase From Pseudomonas Putida and Its Carboligation Reactivity

In this study, the combined use of the selectivity of metal chelate affinity chromatography with the capacity of epoxy supports to immobilize poly‐His‐tagged recombinant benzoylformate decarboxylase from Pseudomonas putida (BFD, E.C. 4.1.1.7) via covalent attachment is shown. This was achieved by designing tailor‐made magnetic chelate–epoxy supports. In order to selectively adsorb and then covalently immobilize the poly‐His‐tagged BFD, the epoxy groups (300 µmol epoxy groups/g support) and a very small density of Co²⁺‐chelate groups (38 µmol Co²⁺/g support) was introduced onto magnetic supports. That is, it was possible to accomplish, in a simple manner, the purification and covalent immobilization of a histidine‐tagged recombinant BFD. The magnetically responsive biocatalyst was tested to catalyze the carboligation reactions. The benzoin condensation reactions were performed with this simple and convenient heterogeneous biocatalyst and were comparable to that of a free‐enzyme‐catalyzed reaction. The enantiomeric excess (ee) of (R)‐benzoin was obtained at 99 ± 2% for the free enzyme and 96 ± 3% for the immobilized enzyme. To test the stability of the covalently immobilized enzyme, the immobilized enzyme was reused in five reaction cycles for the formation of chiral 2‐hydroxypropiophenone (2‐HPP) from benzaldehyde and acetaldehyde, and it retained 96% of its original activity after five reaction cycles. Chirality 27:635–642, 2015. © 2015 Wiley Periodicals, Inc.     

Immobilization of enzymes on Spheron: 2. β-Amylase — The development of a column reactor—separator

The titanium-chelation method has been used to immobilize β-amylase (1,4-α-d-glucan maltohydrolase, EC 3.2.1.2) on to Spheron. On various grades of Spheron, protein coupling yields of 56–76% were obtained with barley and sweet-potato β-amylases. The specific enzymic activities of the immobilized enzymes fell in the range 3.7–7.6% of those of the soluble enzymes. The immobilized enzymes were more stable than the soluble, especially in the presence of l-cysteine and serum albumin. The presence of cysteine and serum albumin brought about increases in activity in the preparations, presumably by regenerating essential thiol groups in the enzyme which had been oxidized during the operations. Maltose could be separated from amylopectin and other large polysaccharides by chromatography on Spheron P100, and a system was developed in which maltose, produced by hydrolysis of amylopectin applied in pulses to a column of immobilized β-amylase, was separated from starting material and by-products on a second column of Spheron P100.     

提高植物磷营养效率（候选）基因研究进展

低磷限制植物产量提高和品质改良是全球亟待解决的土壤养分问题之一,利用现代转基因技术结合常规育种手段培育磷高效新品种是解决这一问题的有效途径。目前,已有百余个磷营养效率候选基因被克隆,但真正用于植物转基因育种实践的却寥寥无几,且进展缓慢。究其原因可能是由于现有候选基因种类繁杂且未系统分类,有些基因的功能尚未明确,缺少克隆与育种交流平台等问题。鉴于此,本文将目前已克隆的植物磷营养效率候选基因按照其功能不同进行分析,对基因的生物学功能及其潜在应用价值进行归纳总结。这不仅为分子生物学家选择目标基因,解析植物磷高效分子机制提供参考,同时为育种学家进行基因转化,培育磷高效新品种搭建平台。     

Ice And The Origin Of Life

Sea ice occurs abundantly at the polar caps of the Earth and, probably, of many other planets. Its static and dynamic properties that may be important for prebiotic and early biotic reactions are described. It concentrates substrates and has many features that are important for catalytical actions. We propose that it provided optimal conditions for the early replication of nucleic acids and the RNA world. We repeated a famous prebiotic experiment, the poly-uridylic acid-instructed synthesis of polyadenylic acid from adenylic acid imidazolides in artificial sea ice, simulating the dynamic variability of real sea ice by cyclic temperature variation. Poly(A) was obtained in high yield and reached nucleotide chain lengths up to 400 containing predominantly 3′→ 5′ linkages.