Some properties of aminopeptidase associated with rat brain cortical synaptosomes

1983 ◽  
Vol 61 (11) ◽  
pp. 1185-1190 ◽  
Author(s):  
William W.-C. Chan ◽  
Wolfgang Demmer ◽  
Karl Brand
Keyword(s):  
Rat Brain ◽  
Leucine Aminopeptidase ◽  
Single Species ◽  
Bound State ◽  
Spectrophotometric Assay ◽  
Diethyl Pyrocarbonate ◽  
Kinetics Of ◽  
The Brain

To understand the breakdown of peptides in the brain, we studied the aminopeptidase associated with synaptosome particles. A continuous spectrophotometric assay in stirred cuvettes was used to follow the kinetics of inactivation by EDTA and by diethyl pyrocarbonate. The sensitivity of the enzyme towards puromycin and leucine hydroxamate was also determined. The results are consistent with the presence of a single species of aminopeptidase in freshly prepared synaptosome. This enzyme is capable of degrading Met-enkephalin in vitro and is distinct from microsomal leucine aminopeptidase. Storage of synaptosomes by freezing and subsequent thawing changed some properties of the enzyme and partially solubilized the enzyme. These studies suggest that there are advantages in studying the enzyme in its native particle-bound state.

Effect of pH and inhibitors on beta-amyloid fibril assembly

1996 ◽  
Vol 54 ◽  
pp. 752-753
Author(s):  
Beverly E. Maleeff ◽  
Timothy K. Hart ◽  
Stephen J. Wood ◽  
Ronald Wetzel
Keyword(s):  
Amyloid Fibril ◽  
Peptide Fragment ◽  
Hydrophobic Peptides ◽  
Amyloid Fibril Formation ◽  
Effects Of Ph ◽  
Severity Of The Disease ◽  
Kinetics Of ◽  
The Brain

Alzheimer's disease is characterized post-mortem in part by abnormal extracellular neuritic plaques found in brain tissue. There appears to be a correlation between the severity of Alzheimer's dementia in vivo and the number of plaques found in particular areas of the brain. These plaques are known to be the deposition sites of fibrils of the protein β-amyloid. It is thought that if the assembly of these plaques could be inhibited, the severity of the disease would be decreased. The peptide fragment Aβ, a precursor of the p-amyloid protein, has a 40 amino acid sequence, and has been shown to be toxic to neuronal cells in culture after an aging process of several days. This toxicity corresponds to the kinetics of in vitro amyloid fibril formation. In this study, we report the biochemical and ultrastructural effects of pH and the inhibitory agent hexadecyl-N-methylpiperidinium (HMP) bromide, one of a class of ionic micellar detergents known to be capable of solubilizing hydrophobic peptides, on the in vitro assembly of the peptide fragment Aβ.

scholarly journals Kinetics of a nucleoside release from lactide-caprolactone and lactide-glycolide polymers in vitro.

2000 ◽  
Vol 47 (1) ◽  
pp. 59-64
Author(s):  
T Kryczka ◽  
P Grieb ◽  
M Bero ◽  
J Kasperczyk ◽  
P Dobrzynski
Keyword(s):  
Formation Rate ◽  
Local Treatment ◽  
Extracellular Fluid ◽  
Brain Extracellular Fluid ◽  
Artificial Cerebrospinal Fluid ◽  
Fluid Formation ◽  
Further Development ◽  
Kinetics Of ◽  
The Brain

We assessed the rate of release of a model nucleoside (adenosine, 5%, w/w) from nine different lactide-glycolide or lactide-caprolactone polymers. The polymer discs were eluted every second day with an artificial cerebrospinal fluid at the elution rate roughly approximating the brain extracellular fluid formation rate. Adenosine in eluate samples was assayed by HPLC. Three polymers exhibited a relatively constant release of adenosine for over four weeks, resulting in micromolar concentrations of nucleoside in the eluate. This points to the necessity of further development of polymers of this types as intracerebral nucleoside delivery systems for local treatment of brain tumors.

The in vitro dissociation kinetics of (R,R)-[125I]4IQNB is reflected in the in vivo washout of the radioligand from rat brain

Life Sciences ◽  
1992 ◽  
Vol 50 (9) ◽  
pp. 629-637 ◽  
Author(s):  
Raymond E. Gibson ◽  
Terry Moody ◽  
Timothy A. Schneidau ◽  
Elaine M. Jagoda ◽  
Richard C. Reba
Keyword(s):  
Rat Brain ◽  
Dissociation Kinetics ◽  
Kinetics Of

Postnatal development and kinetics of [3H]gaboxadol binding in rat brain: In vitro homogenate binding and quantitative autoradiography

2007 ◽  
Vol 1170 ◽  
pp. 39-47 ◽  
Author(s):  
Anne Friemel ◽  
Bjarke Ebert ◽  
Pete H. Hutson ◽  
Peter Brust ◽  
Karen Nieber ◽  
...  
Keyword(s):  
Rat Brain ◽  
Postnatal Development ◽  
Quantitative Autoradiography ◽  
Kinetics Of

scholarly journals Inhibition of hsc70-catalysed clathrin uncoating by HSJ1 proteins

1996 ◽  
Vol 319 (1) ◽  
pp. 103-108 ◽  
Author(s):  
Michael E CHEETHAM ◽  
Brian H. ANDERTON ◽  
Antony P. JACKSON
Keyword(s):  
Heat Shock ◽  
Molecular Chaperones ◽  
Coated Vesicles ◽  
Coated Vesicle ◽  
General Factor ◽  
Vesicle Preparation ◽  
Specific Proteins ◽  
Kinetics Of ◽  
The Brain

The uncoating of clathrin-coated vesicles can be mediated in vitro by the ‘uncoating ATPase’ that has been identified as the constitutive 70 kDa heat shock protein (hsp70), hsc70. It is now established that the activity of hsp70 proteins can be regulated by another family of molecular chaperones, the DnaJ family. In this study, we have investigated the effects of DnaJ-like proteins (the human neuron-specific proteins HSJ1a and HSJ1b) on clathrin uncoating. In order to measure the kinetics of clathrin release from coated vesicles, we have developed a quantitative, two-site ELISA for clathrin triskelions and demonstrated that stoichiometric amounts of HSJ1 proteins inhibit the initial burst of hsc70-mediated clathrin uncoating by over 40%. This inhibition is not a consequence of ADP binding by hsc70 or the aggregation of hsc70, but correlates with an increase in the hsc70 associated with the coated vesicle fraction, suggesting that the inhibition is a consequence of a non-productive stabilization of hsc70 with a component of the coated vesicle fraction. These results strongly suggest that HSJ1 proteins interfere with an endogenous DnaJ-like protein that is involved in uncoating. Recent evidence suggests that the brain-specific vesicle-associated protein auxilin could play such a role. Athough we find no evidence for auxilin in our coated vesicle preparation, our results predict that an auxilin-like protein will be a general factor in clathrin uncoating.

Immunochemical and Biochemical Evidence for Expression of Phenobarbital-and 3-Methylcholanthrene-Inducible Isoenzymes of Cytochrome P450 in Rat Brain

1998 ◽  
Vol 17 (6) ◽  
pp. 619-630 ◽  
Author(s):  
Devendra Parmar ◽  
Alok Dhawan ◽  
Monika Dayal ◽  
Prahlad K. Seth
Keyword(s):  
Cytochrome P450 ◽  
Rat Brain ◽  
Western Blotting ◽  
Polyclonal Antibodies ◽  
Biochemical Evidence ◽  
Catalytic Activities ◽  
Brain Microsomes ◽  
The Brain

Expression of P450 1A1l 1A2 and 2 B1l 2B2 isoenzymes in rat brain was studied by Western blotting, using polyclonal antibodies raised against hepatic P450 1A1l 1A2 and 2B1l 2B2 isoenzymes. In addition, biochemical characterizations of the catalytic activities, pen toxyresorufin O-dealkylation (PROD) and ethoxyre-sorufin O-deethylation (EROD), selective for P450 2B1l 2B2 (PROD) and P450 1A1l 1A2 (EROD), were performed with rat brain microsomes. Control rat brain microsomes did not crossreact with either of the antibodies, whereas microsomes obtained from 3-methylcholanthrene (MC)-pretreated rats revealed significant immunoreactivity with anti-P450 1A1l 1A2. Similar results were observed with phenobarbital (PB)-pretreated rats, with the brain microsomes exhibiting significant immunoreactivity with anti-P450 2B1l 2B2. The induction in the P450 isoenzymes after PB or MC pretreatment was much less in the brain in comparison to the liver. Enzymatic studies indicated that the activities of PROD and EROD were induced in brain 3—4 fold by PB and MC pretreatment, respectively, and were almost completely inhibited on in vitro addition of anti-P450 2B1l 2B2 and 1A1l 1A2. These data demonstrate the expression of P4501A1l 1A2 and 2B1l 2B2 isoenzymes in the brain and indicate that, as in liver, these isoenzymes catalyze EROD and PROD, respectively, in the rat brain.

scholarly journals Insulin differentially affects the distribution kinetics of amyloid beta 40 and 42 in plasma and brain

2017 ◽  
Vol 38 (5) ◽  
pp. 904-918 ◽  
Author(s):  
Suresh Kumar Swaminathan ◽  
Kristen M Ahlschwede ◽  
Vidur Sarma ◽  
Geoffry L Curran ◽  
Rajesh S Omtri ◽  
...  
Keyword(s):  
Amyloid Beta ◽  
Amyloid Beta Peptides ◽  
Beta Peptides ◽  
Distribution Kinetics ◽  
In Vitro Bbb Model ◽  
First Time ◽  
Kinetics Of ◽  
The Brain ◽  
Distinct Distribution

Impaired brain clearance of amyloid-beta peptides (Aβ) 40 and 42 across the blood–brain barrier (BBB) is believed to be one of the pathways responsible for Alzheimer’s disease (AD) pathogenesis. Hyperinsulinemia prevalent in type II diabetes was shown to damage cerebral vasculature and increase Aβ accumulation in AD brain. However, there is no clarity on how aberrations in peripheral insulin levels affect Aβ accumulation in the brain. This study describes, for the first time, an intricate relation between plasma insulin and Aβ transport at the BBB. Upon peripheral insulin administration in wild-type mice: the plasma clearance of Aβ40 increased, but Aβ42 clearance reduced; the plasma-to-brain influx of Aβ40 increased, and that of Aβ42 reduced; and the clearance of intracerebrally injected Aβ40 decreased, whereas Aβ42 clearance increased. In hCMEC/D3 monolayers (in vitro BBB model) exposed to insulin, the luminal uptake and luminal-to-abluminal permeability of Aβ40 increased and that of Aβ42 reduced; the abluminal-to-luminal permeability of Aβ40 decreased, whereas Aβ42 permeability increased. Moreover, Aβ cellular trafficking machinery was altered. In summary, Aβ40 and Aβ42 demonstrated distinct distribution kinetics in plasma and brain compartments, and insulin differentially modulated their distribution. Cerebrovascular disease and metabolic disorders may disrupt this intricate homeostasis and aggravate AD pathology.

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