Abstract: The present invention relates to the field of biotechnologies. Disclosed are an enzyme composition for preparing ?-nicotinamide mononucleotide (NMN), and an application thereof. In the present invention, by using adenosine and nicotinamide as raw materials, D-ribose 1-phosphate and a nicotinamide ribose intermediate are generated under enzyme catalysis of an enzyme composition of a PNP enzyme and an NRK enzyme, and finally NMN is obtained; only two enzymes need to be involved in the whole reaction system, and the by-product adenine can be recycled. Moreover, only one molecule of ATP needs to be consumed for generating one molecule of NMN, thereby greatly reducing the process cost. The reaction of synthesizing NMN by NRK enzyme catalysis in the last step is irreversible, and thus, the substrate conversion rate can be greatly improved and the production cost can be further reduced.

Abstract: The present invention relates to the technical field of biosynthesis, and in particular to a method for preparing S-nicotine. Amine oxidase is utilized to oxidize 1-methylpyrrolidine into corresponding imine, and then the imine and nicotinic acid are condensed and decarboxylated under the catalysis of nicotine synthetase to obtain a final product S-nicotine. The S-nicotine having specific chirality can be obtained by means of two-step reaction in a reaction system, the synthetic route is short, the yield is high, the reaction conditions are mild, and large-scale production is easy to achieve; moreover, raw materials are wide in source, low in price, low in production cost and environmentally friendly, the production cost of nicotine is remarkably reduced, and the requirements of current green industrial production can be better satisfied.

Abstract: A compound enzyme, comprising L-histidine methylase, halogen methyltransferase and trimethylhistidine sulfurylase. L-histidine is catalyzed by L-histidine methylase and halogen methyltransferase to obtain trimethylhistidine, and then is catalyzed by trimethylhistidine sulfurase to obtain the L-ergothioneine. The method can realize conversion from L-histidine to L-ergothioneine only in two steps. Moreover, SAM enzyme is regenerated, such that the usage amount of the SAM enzyme is greatly reduced. Therefore, the method greatly reduces the raw material cost. Moreover, the method is high in reaction concentration (about 30 g/L), simple in process and good in industrial production prospect.

Abstract: The present invention relates to the technical field of biochemistry. Disclosed are a mutant enzyme, the use thereof and a process for preparing a tripeptide by using an enzymatic method. The mutant enzyme comprises: glycine and L-histidine ligase GHS, and tripeptide ligase HKS; or a fusion enzyme of the two. Glycine and L-histidine ligase activity is achieved by means of modifying an Lal enzyme, so as to obtain the GHS enzyme; and the ability for synthesizing dipeptide glycine-L-histidine and L-lysine is achieved by means of using a gshB enzyme, so as to obtain the HKS enzyme. On this basis, the GHS enzyme is further fused with the HKS enzyme by means of using a polypeptide chain, and then a bifunctional enzyme GHKS that links glycine, L-histidine and L-lysine in one step can be constructed, so that a tripeptide is conveniently prepared with a high yield.

Abstract: An online system provides content items including URLs of third party websites to client devices. The client devices prefetch data from the third party website via the URL. The online system controls the prefetch rate for the client devices based on information received from the client devices. The online system may reduce the prefetch rate if an aggregate number of prefetches from the third party website during a time interval exceeds a prefetch quota. The online system may reduce the prefetch rate if the client devices indicate poor performance of the third party. The online system may determine whether to prefetch data from a URL included in a content item based on a likelihood of the user ignoring the content item if here is a delay in loading of the content item in the client device.

Abstract: An anti-back mechanism for a drug delivery device according to the present application includes a retaining groove, a position retaining protrusion and a clamping groove. The retaining groove is provided on a push rod. The position retaining protrusion is provided in the drug delivery device. The clamping groove has an accommodation cavity into which the position retaining protrusion is inserted. The position retaining protrusion is provided on a ring having a notch and may be clamped with respect to the push rod when the position retaining protrusion is squeezed. When the position retaining protrusion is subjected to a reverse thrust from a cartridge holder of the drug delivery device, the position retaining protrusion may move in a direction opposite to an injection direction, be inserted into the clamping groove to be clamped, and be hooked to the retaining groove to be locked.

Abstract: An online system accounts for measures of quality of content items when selecting content items for presentation to users. For a content item including a link to a landing page outside a domain of the online system, the measure of quality accounts for a likelihood of a user presented with the content item returning to the online system after less than a threshold amount of time accessing the landing page. The measure of quality of the content item is based on the likelihood of the user returning to the online system after less than the threshold amount of time relative to likelihoods of other users returning to the online system after less than the threshold amount of time. The measure of quality of the content item is affected by a difference between the likelihood determined for the user and the likelihoods determined for other users.

Abstract: Provided is a method for solid phase synthesis of liraglutide, comprising the following steps: A), Fmoc-Gly-resin being obtained by coupling resin solid phase carrier with glycine with N-end protected by Fmoc(Fmoc-Gly-OH) in the presence of activator system; B) according to the peptide sequence of the main chain of liraglutide, successively coupling with amino acids with N-ends protected by Fmoc and protected side chains by the method for solid phase synthesis, wherein lysine employs Fmoc-Lys(Alloc)-OH; C) removing the protective group, Alloc, from the side chain of lysine; D) coupling the side chain of lysine with Palmitoyl-Glu-OtBu by the method for solid phase synthesis; E) cleavage, removing protection groups and resin to obtain crude liraglutide; F) purifying and lyophilizing to obtain liraglutide.

Abstract: The present invention relates to the field of biomedicine, and in particular, to a method for purifying solid-phase synthetic crude liraglutide. The method comprises: dissolving solid-phase synthetic crude liraglutide in an aqueous acetonitrile solution to obtain a crude peptide solution; and obtaining liraglutide with high purity and high yield through four-step HPLC purification.

Abstract: Provided is a method for solid phase synthesis of liraglutide, comprising the following steps: A), Fmoc-Gly-resin being obtained by coupling resin solid phase carrier with glycine with N-end protected by Fmoc(Fmoc-Gly-OH) in the presence of activator system; B) according to the peptide sequence of the main chain of liraglutide, successively coupling with amino acids with N-ends protected by Fmoc and protected side chains by the method for solid phase synthesis, wherein lysine employs Fmoc-Lys(Alloc)-OH; C) removing the protective group, Alloc, from the side chain of lysine; D) couplilng the side chain of lysine with Palmitoyl-Glu-Offiu by the method for solid phase synthesis; E) cleavage, removing protection groups and resin to obtain crude liraglutide; F) purifying and lyophilizing to obtain liraglutide.

Abstract: A social networking system selects advertisements for its users using collaborative filtering based on the users' interactions with objects in the social networking system. The objects may be games, pages, groups, deals, messages, content items, advertisements, or any other object with which a user may interact in the system. The system may identify a viewing user's interaction with a first object, determine a second object that is similar to the first object based on interactions of users with both of the objects, and send an advertisement associated with the second object to the viewing user. The system determines a second object based a similarity score between the first object and the second object, which may be a measure of users who have interacted with both objects and may be normalized by a number of user interactions by the users with the objects.

Abstract: Systems and processes disclosed herein relate to the utilization of direct contact condensing to provide heat to a solvent regeneration loop in an acid gas removal process. A first direct contact condenser can be included in the upper section of a concentrator that removes acid gas from a rich solvent stream. A first slip stream can be heated in the first direct contact condenser and can be combined with the rich solvent stream in the lower section of the stripper. A second direct contact condenser can be included in the lower section of an absorber that removes acid gas from a feed gas. A second slip stream can be heated in the second direct contact condenser, and can be combined with the rich solvent stream before the rich solvent stream is provided to the concentrator.

Abstract: Systems and processes disclosed herein relate to the utilization of direct contact condensing to provide heat to a solvent regeneration loop in an acid gas removal process. A first direct contact condenser can be included in the upper section of a concentrator that removes acid gas from a rich solvent stream. A first slip stream can be heated in the first direct contact condenser and can be combined with the rich solvent stream in the lower section of the stripper. A second direct contact condenser can be included in the lower section of an absorber that removes acid gas from a feed gas. A second slip stream can be heated in the second direct contact condenser, and can be combined with the rich solvent stream before the rich solvent stream is provided to the concentrator.