Functions of Ubiquitin Specific Proteases Essay

The proteins were visualized using the Coomassie Blue stain. Coomassie Blue binds non-specifically and nearly stoichiometrically to all proteins [5]. Proteins have a higher affinity to the dye than the polyacrylamide gel; therefore, after removing excess stain, the protein bands can be visualized [4]. This non-selective binding was essential for analyzing the purity in each invertase fraction, as both non-target proteins and invertase were visualized. As shown in Fig. 1., excluding invertase fraction 2, the general trend was that the number of protein bands decreased from fractions 1 to 4, while a band with a molecular weight around 1.2 x 102 kDa became more prominent and intense. These results were expected for a successful purification [4]. During experiment 6, it was observed that the specific activity increased during each successive fraction. Since the same amount of protein, from each invertase

The Bovine herpsvirus 1 (BoHV-1) produces the protein UL49.5, which also interferes with the transport of peptides via TAP [13]. The BoHV-1 UL49.5 interacts with the TAP core particle, through its transmembrane domain and ER-luminal domain, and prevents rearrangements in the structure of TAP. These rearrangements typically occur subsequent to the binding of antigenic peptides and ATP. Such rearrangements influence the movement of TAP, as during peptide transport the transporter molecules move slower than those not bound to peptides. However, the binding of UL49.5 hinders such changes in TAP mobility by preventing structural rearrangements, which are essential for the translocation of peptides. BoHV-1 UL49.5 also interrupts peptide transport through promoting the degradation of the TAP1 and TAP2 subunits. This is achieved by the C-terminal cytoplasmic tail of UL49.5 which connects the TAP and UL49.5 complex to ubiquitin, thereby targeting it for proteasome mediated degradation [12, 13]. This transporter is also a key target for other viral evasion proteins (Table

This Lab Report is an analysis of the results of a two-part experiment. In the first part, we used a gel filtration column to separate the components of a mixture composed of protein and non-protein molecules. By doing so we hoped to obtain fractions that contained single components of the mixture, while also gaining insight into the relative molecular weight of each component compared to each other. We would then plot these fractions onto nitrocellulose paper in order to determine which fractions had protein. In the second part, we would use the fractions which we had determined had protein to conduct an SDS-PAGE. By doing so we hoped to determine an estimate on the molecular weight of the proteins present in each fraction by comparing it to a tracker dye composed of a variety of molecules of differing molecular weight.

Protein Assay: The Pierce BCA Protein Assay (Thermo Scientific) is a detergent-compatible formulation based on bicinchoninic acid (BCA) for the colorimetric detection and quantitation of total protein concentration. A series of standard solution of Bovine Serum Albumin (BSA) ranging from 0-2000 µg/ml was prepared from a stock solution of 2 mg/ml BSA. 25ul of diluted crude (1:500, 1:250), desalted (1:100, 1:50), and 6 peak fractions from cibarcon blue column (1:10, 1:5) were loaded in microplate along with 175ul of BCA working reagent. Microplate was incubated for 30min at 370C and then the absorbance was measured at 562nm.

Having removed the detergent, the protein will refold. As shown by the Anfinsen experiment the polypeptide sequence determines the folding and therefore the three dimensional structure. As the polypeptide sequence is unaltered refolding can occur through the process of nucleation aggregation and compaction. In order to test that the protein was no longer denatured, the absorbency of the solution at 412nm could be measured and compared with the graph in figure 1 above, it should match the plot of standard ovalbumin in the absence of SDS.

Proteins are the metabolic workhorses of the cell; they engage in a variety of essential activities ranging from enzymatically catabolizing macromolecular food sources to serving as structural components that maintain cell stability. Maximizing protein function relies on intricate non-covalent interactions occurring on the secondary, tertiary, and quaternary levels that help determine the overall shape of the protein. In their native states, proteins will assume the most energetically favorable configuration. Occasionally however, cells are exposed to exogenous disruptions such as heat stress. Heat Stress can compromise protein three-dimensional structure. Hydrophobic residues tend to be buried in the interior of the protein but when

There are many types of ubiquitin ligases in cells. However, we can make some candidate groups of targeting E3 based on the bioinformatics database.

The filter flask, vacuum, and SNAP i.d. 2.0 were securely connected with tubing. The proteins were transferred to a membrane and was incubated with primary antibody. The primary antibody was then washed three times. Afterwards a secondary antibody was added and the same procedure was repeated. 10mL of 5-bromo-4-chloro-3-indoyl phosphate/ nitro blue tetrazolium chloride chromogenic substrate solution was added to the blot which was then wrapped with aluminum foil and labeled.

Western blotting - In Western blotting first, the macromolecules have to be separated via gel electrophoresis. The molecules now separated by electrophoresis are blotted onto either a nitrocellulose or a polyvinylidene difluoride (PVDF) membrane (a second matrix). To inhibit the binding of nonspecific antibodies to the membrane surface it is subsequently blocked. Then a complex is formed (a probe) from the protein that was transferred and an enzyme linked with an antibody. The enzyme is supplied a substrate then the 2 together should create a product e.g. chromogenic precipitate that can be detected. Detection methods with most sensitivity use chemiluminescent substrate because light is a by-product of the reaction between the substrate and the enzyme. The output of the light can be measured using a CCD camera or on the other hand, antibodies that have been tagged with fluorescents that are detected with a fluorescence imaging system can be used (Thermo-Fisher Scientific 2015).

Chaperones are proteins that ensure the correct folding of the CFTR within the endoplasmic reticulum. Hsp70 is an important cytosolic chaperone that complexes with CFTR and reduces aggregation [5]. The CFTR passes through the endoplasmic reticulum-associated degradation (ERAD) after folding in the ER. This quality control system involves the ubiquitin proteasome system (UPS) for which CFTR is a substrate [16]. If a protein is molded and targeted for degradation, then ubiquitin will covalently attach to lysine residues on the CFTR. Three enzymes are required for the process of ubiquitylation: E1 ubiquitin activating enzymes, E2 ubiquitin conjugating enzymes, and E3 ubiquitin protein ligases. E1 enzymes are activated through hydrolysis of ATP, which creates an activated ubiquitin that is transferred to an E2 active site. The activated ubiquitin is then covalently bound to a lysine on the protein by an E3 ligase. A polyubiquitin chain is then formed as ubiquitin molecules link together, and if there are four or more then the misfolded CFTR chain is removed form the ER membrane and targeted for degradation by the 26S proteasome

During that time we learned various steps and methods to purifying protein. We segwayed into enzymes and their ability to catalyze reactions by lowering the activation energy. We also learned the different classifications that specific enzymes depending on the reactions they catalyze. For example, enzymes that are involved in catalyzing hydrolysis reactions are known as hydrolases. Lastly, we looked at polysaccharides for short-term energy storage and their interactions through glycosidic bondage. Nucleotides were also mentioned and their involvement in DNA and RNA. Concluding the course, we observed lipids and their involvement with long-term energy storage. With all that we have learned, I now reflect and appraise the role that biochemistry plays in my everyday life as well as from a global point of view.

Protein standards were previously loaded into the first rows of the well plate of which the concentrations were as followed; 500 μg/mL, 250 μg/mL, 125 μg/mL, 62.5 μg/mL, and 0 μg/mL (PBS only). After making note of the rows used the plates were loaded onto the selected protein row, followed by the addition of 200 μL of Bradford reagent to each well using a multichannel pipette. The absorbance of the plate was read at 595nm and recorded. The NT-2 and LPS-2 protein sample tubes were labeled for easy identification in the following lab and the protein samples were stored in the freezer for 1 week.

This assignment will outline the function of proteins in living organisms and the important roles of different types of protein. “Protein composes 10-30% of cell mass and is the basic structural material of the body” (Marieb E.N.M et al, 2004). Protein is a nutrient that living organisms need to exist and grow, as well as water being a key feature. “All protein contains carbon, oxygen, hydrogen and nitrogen” (Marieb E.N.M et al, 2004). Amino acids form links of 20, “The sequences at which they are bound together produces proteins that vary widely in both structure and function” (Marieb E.N.M et al, 2004).

For the second part of the experiment, one had to use the knowledge learn from viewing protein molecules in FirstGlance in Jmol to analyze the protein PDB ID: 4EEY. The analysis of this protein was done using the RSCB protein data bank (PDB) at (http://www.rcsb.org/pdb/home/home.do).2

Overexpression of the HEPN domain in HeLa cells following three hours of starvation indicates that sacsin plays a key role in lysosomal transport due to the reduced efficiency of perinuclear lysosomal clustering. HEPN’s property of dimerizing may be disrupting the function of with full-length sacsin by preventing endogenous sacsin from dimerizing within the cell. Thus, dimerization may be essential to sacsin’s function, particularly for binding JIP3, which is necessary for lysosomal transport7. HATPase 3 overexpression may be occupying JIP3 binding, but was not found to disrupt lysosomal localization following starvation, perhaps due to the truncated size of this deletion construct.