Large-scale crystallization as an intermediate processing step in insulin downstream process: explored advantages and identified tool for process intensification

The rising global prevalence of diabetes and increasing demand for insulin, calls for an increase in accessibility and affordability of insulin drugs through efficient and cost-effective manufacturing processes. Often downstream operations become manufacturing bottlenecks while processing a high volume of product. Thus, process integration and intensification play an important role in reducing process steps and time, volume reduction, and lower equipment footprints, which brings additional process efficiencies and lowers the production cost. Manufacturers thrive to optimize existing unit operation to maximize its benefit replacing with simple but different efficient technologies. In this manuscript, the typical property of insulin in forming the pH-dependent zinc-insulin complex is explored. The benefit of zinc chloride precipitation/crystallization has been shown to increase the in-process product purity by reducing the product and process-related impurities. Incorporation of such unit operation in the insulin process has also a clear potential for replacing the high cost involved capture chromatography step. Same time, the reduction in volume of operation, buffer consumption, equipment footprint, and capabilities of product long time storage brings manufacturing flexibility and efficiencies. The data and capabilities of simple operation captured here would be significantly helpful for insulins and other biosimilar manufacturer to make progresses on cost-effective productions.

Expression, purification and crystallization of the ecto-enzymatic domain of rat E-NTPDase1 CD39

CD39 is a prototype member of the ecto-nucleoside triphosphate diphosphohydrolase family that hydrolyzes extracellular nucleoside diphosphates and triphosphates in the presence of divalent cations. Here, the expression, purification and crystallization of the ecto-enzymatic domain of rat CD39, sCD39, are described. The 67 kDa secreted soluble glycoprotein was recombinantly overexpressed in a glycosylation mutant CHO line, Lec.3.2.8.1, and purified from conditioned media. Diffraction-quality crystals of sCD39 were produced by the vapor-diffusion method using PEG 3350 and ammonium dihydrogen phosphate as precipitants. The enzyme crystallized in a primitive trigonal form in space group P3(2), with unit-cell parameters a = b = 118.1, c = 81.6 A and with two sCD39 copies in the asymmetric unit. Several low- to medium-resolution diffraction data sets were collected using an in-house X-ray source. Analysis of the intensity statistics showed that the crystals were invariably merohedrally twinned with a high twin fraction. For initial phasing, a molecular-replacement search was performed against the complete 3.2 A data set using a maximum-likelihood molecular-replacement method as implemented in Phaser. The initial model of the two sCD39 monomers was placed into the P3(2) lattice and rigid-body refined and position-minimized with PHENIX.

The Structure of the Lingo-1 Ectodomain, a Module Implicated in Central Nervous System Repair Inhibition

Nogo receptor (NgR)-mediated control of axon growth relies on the central nervous system-specific type I transmembrane protein Lingo-1. Interactions between Lingo-1 and NgR, along with a complementary co-receptor, result in neurite and axonal collapse. In addition, the inhibitory role of Lingo-1 is particularly important in regulation of oligodendrocyte differentiation and myelination, suggesting that pharmacological modulation of Lingo-1 function could be a novel approach for nerve repair and remyelination therapies. Here we report on the crystal structure of the ligand-binding ectodomain of human Lingo-1 and show it has a bimodular, kinked structure composed of leucine-rich repeat (LRR) and immunoglobulin (Ig)-like modules. The structure, together with biophysical analysis of its solution properties, reveals that in the crystals and in solution Lingo-1 persistently associates with itself to form a stable tetramer and that it is its LRR-Ig-composite fold that drives such assembly. Specifically, in the crystal structure protomers of Lingo-1 associate in a ring-shaped tetramer, with each LRR domain filling an open cleft in an adjacent protomer. The tetramer buries a large surface area (9,200 A2) and may serve as an efficient scaffold to simultaneously bind and assemble the NgR complex components during activation on a membrane. Potential functional binding sites that can be identified on the ectodomain surface, including the site of self-recognition, suggest a model for protein assembly on the membrane.