Expression Of Recombinant Tick Histamine-Binding Protein Lab Report

Expression Of Recombinant Tick Histamine-Binding Protein - Lab Report Example To facilitate further studies regarding the structure and function of HBP, there should be an efficient means by which HBP can be made available. For this, Pichia pastoris expression system was assessed for its competence in producing recombinant HBP. This was chosen for its effectiveness in glycosylating recombinant proteins. On the other hand, the HBP gene sequence used for this particular study was from cattle tick, Rhipicephalus microplus, which is considered to be an agricultural pest. If found to have therapeutic effect, the despised insect will be given a newly-discovered purpose. Culture and induction of transformed P. pastoris was able to produce c-myc epitope-containing proteins, potentially containing TC11485, as detected through dot blot and Western blot analysis. Future researches involve purification and characterization of the recombinant TC11485. Introduction Lipocalins 1. The structure-function relation in lipocalins Lipocalins are monomeric globular proteins compris ed of a single polypeptide with 150-200 amino acid residues, and ubiquitous in all life forms. In fact, these proteins are abundant in plasma, tissue and secretory fluids of humans. Despite its weak sequence homology, they are characterized by a tertiary structural level of a conserved ?-barrel configuration with an amino-and carboxy-terminal ?-helix attachment, contributing to their similarities in function, which will be discussed in the later sections. The barrel is shaped like a cone, in which the tip is a hydrophobic core that protects the parcel, and the base open to solvent acts as an entry point into the cavity. In fact, the term lipocalin is derived from ‘calyx’, which is the Greek and Latin word for drinking vessel (Cheng, 2010; Schlehuber and Skerra, 2005). Classification of lipocalins is based on variations in the length of the terminal segments. Aside from the highly conserved tertiary structure, lipocalins also exhibit similar arrangement of exons and intr ons in their genes’ coding sequences (Cheng, 2010). Understandably, each lipocalin has a distinct amino acid sequence. For human lipocalins, a single unpaired cysteine (Cys) residue allows intermolecular covalent binding of a lipocalin to another protein. Apolipoprotein D (ApoD) binds with apolipoprotein A-II, and NGAL associates with matrix metalloproteinase IX Other than being differentiated based on amino acid sequence, lipocalins vary in the shapes that their structures can assume. Logically, capability for such changes influences the function of the protein. For example, neutrophil gelatinase-associated lipocalin (NGAL) opens more widely to become more funnel-like, while the mouse major urinary protein (MUP) closes the opening of the barrel to totally encapsulate the ligand (Schlehuber and Skerra, 2005). 2. Physiologic role of lipocalins This family of proteins primarily functions to transport or store compounds that are insoluble or chemically sensitive. Among the compo unds transported by lipocalins are hydrophobic vitamins, pheromones, bilins, retinoids, lipids and steroid hormones, play significantly in transcription, enzymatic reactions and metabolism (Schlehuber and Skerra, 2005; Cheng, 2010). They deliver their ligands to the cell membrane receptor or to the targets (such as DNA) themselves. For example, the human plasma retinol-binding protein (RBP), the first lipocalin structurally characterized, transports the insoluble and highly oxidative vitamin A from the stores in the liver to the target tissues . ApoD transports progesterone and arachidonic acid, while NGAL has Fe(III)-enterobactin as its ligand (Schlehuber and Skerra, 2005). 3. Medical significance of lipocalins Because of their