Matrix processing peptidase of mitochondria

The mitochondrial processing peptidase (MPP) and the processing enhancing protein (PEP) cooperate in the proteolytic cleavage of matrix targeting sequences from nuclear-encoded mitochondrial precursor proteins. We have determined the cDNA sequence of Neurospora MPP after expression cloning. MPP appears to contain two domains of approximately equal size which are separated by a loop-like sequence. Considerable structural similarity exists to the recently sequenced yeast MPP as well as to Neurospora and yeast PEP. Four cysteine residues are conserved in Neurospora and yeast MPP. Inactivation of MPP can be achieved by using sulfhydryl reagents. MPP (but not PEP) depends on the presence of divalent metal ions for activity. Both MPP and PEP are synthesized as precursors containing matrix targeting signals which are processed during import into mitochondria by the mature forms of MPP and PEP

Development of biodegradable composite micro-perforated panel made from natural fibre composites with evaluation of its acoustic and mechanical properties

Micro-perforated panel (MPP) has been widely considered as a promising alternative for sound absorption purposes. Plenty of research has been done to improve the sound absorption of MPP but no specific work highlights the material structure effect towards its sound absorption performance. MPP is mostly made from metallic or plastic materials which does not exhibits any pores or tortuous structure and therefore, material structure issue is often being eliminated from analysis. In order to study the material structure effect, alternative material must be used to fabricate MPP. Numerous research found that natural fibre possesses excellent sound absorption properties due to its porous and tortuous structure. Yet, natural fibre has low tolerance towards mechanical processing and thus binder must be incorporated to overcome this shortcoming. This thesis basically describes the development process of biodegradable composite micro-perforated panel (BC-MPP) made from natural fibre (kenaf, wood, and coconut) and polylactic acid (PLA) composites. BC-MPP samples were fabricated with different material composition percentage of natural fibre and PLA. The effect of material composition percentage, perforation ratio, perforation diameter, and air cavity thickness were investigated. The effect of material structure towards the sound absorption performance of BC-MPP sample was studied. It has been found that existence of pores and tortuous structure can indeed influence the sound absorption performance of BC-MPP sample. The sound absorption performance of BC-MPP sample was compared to conventional MPP and it has been found that BC-MPP possessed better sound absorption performance courtesy to its porous and tortuous structure. BC-MPP sample also possessed better tensile strength compared to common sound absorption panel such as medium density fibreboard, hardboard, commercial ceiling board, and plywood

The processing peptidase of yeast mitochondria

Two proteins co-operate in the proteolytic cleavage of mitochondrial precursor proteins: the mitochondrial processing peptidase (MPP) and the processing enhancing protein (PEP). In order to understand the structure and function of this novel peptidase, we have isolated mutants of Saccharomyces cerevisiae which were temperature sensitive in the processing of mitochondrial precursor proteins. Here we report on the mif2 mutation which is deficient in MPP. Mitochondria from the mif2 mutant were able to import precursor proteins, but not to cleave the presequences. The MPP gene was isolated. MPP is a hydrophilic protein consisting of 482 amino acids. Notably, MPP exhibits remarkable sequence similarity to PEP. We speculate that PEP and MPP have a common origin and have evolved into two components with different but mutually complementing functions in processing of precursor proteins

Characterization of the mitochondrial processing peptidase of Neurospora crassa

The mitochondrial processing peptidase (MPP) of Neurospora crassa is constituted by an alpha- and a beta-subunit. We have purified alpha-MPP after expression in Escherichia coli while beta-MPP was purified from mitochondria. A fusion protein between precytochrome b2 and mouse dihydrofolate reductase was expressed in E. coli, and the purified protein was used as substrate for MPP. Both subunits of MPP are required for processing. MPP removes the matrix targeting signal of cytochrome b2 by a single cut, and the resulting presequence peptide is 31 amino acid residues in length. It acts as a competitive inhibitor of processing but has a approximately 30-fold lower affinity for MPP than the preprotein. Competition assays show that MPP recognizes the COOH- terminal portion of the presequence of cytochrome b2 rather than the NH2-terminal part which has the potential to form an amphiphilic helix. Substitution of arginine in position -2 of the matrix targeting sequence of cytochrome b2 prevents processing but not import of a chimeric precursor. Substitution of the tyrosyl residue in position +1 also prevents processing, indicating that MPP interacts with sequences COOH-terminal to the cleavage site. Non-cleavable preprotein is still recognized by MPP. Our data suggest that processing peptidase and import machinery recognize distinct structural elements in preproteins which, however, can be overlapping

Pembangunan modul pembelajaran autocad dan kajian penerimaan pelajar. Satu kajian kes di Politeknik Kota Bharu

Modul Pengajaran dan Pembelajaran AutoCAD (MPP) merupakan satu media pengajaran yang mengandungi asas-asas mengenai komputer, perisian AutoCAD 2000 dan langkah-langkah berperingkat membuat lukisan teknikal menggunakan AutoCAD 2000. Kajian ini adalah bertujuan untuk menilai sejauh mana MPP ini boleh digunakan dalam proses pengajaran dan pembelajaran dalam aspek kesesuaian isi kandungan, sifat mesra pengguna dan kebolehlaksanaannya. Respondan untuk kajian ini ialah seramai 42 orang pelajar Diploma Kejuruteraan Elektrik Politeknik Kota Bharu. Untuk kajian ini instrumen yang digunakan ialah borang soal selidik di mana penilaian dilakukan berdasarkan persepsi responden terhadap MPP. Data-data yang dikumpulkan dianalisis menggunakan SPSS VI1.0 yang melibatkan skor min. Hasil kajian melaporkan dapatan yang diperolehi berkenaan penerimaan terhadap MPP. Hasil dapatan kajian menunjukkan penerimaan yang positif terhadap MPP oleh pelajar dan ianya mempimyai kebolehlaksanaan yang tinggi (skor min = 3.96) untuk diaplikasikan dalam proses pengajaran dan pembelajaran. Walaubagaimanapun pengkaji percaya MPP ini mempunyai ruang untuk penambahbaikan seperti saranan oleh penilai yang mengesahkan MPP ini agar ia lebih menarik dan sesuai digunakan pada masa depan

Implementation of the Multiple Point Principle in the Two-Higgs Doublet Model of type II

The multiple point principle (MPP) is applied to the non--supersymmetric two-Higgs doublet extension of the Standard Model (SM). The existence of a large set of degenerate vacua at some high energy scale caused by the MPP results in a few relations between Higgs self-coupling constants which can be examined at future colliders. The numerical analysis reveals that these MPP conditions constrain the mass of the SM--like Higgs boson to lie below 180 GeV for a wide set of MPP scales $\Lambda$ and $\tan\beta$.Comment: 26 pages, 3 figures, some minor changes to the tex

A generic applications subroutine library for the MPP

A new methodology to increase the utility of the Massively Parallel Processor (MPP) was developed, and is presented as an addition to the current methods of using the MPP. This methodology provides for the development of an MPP side abstraction layer that is callable from any host side high level language. Routines in the abstraction layer have the option of using a powerful software tool for accessing the stager as virtual memory. An additional abstraction layer that allows for remote access to the MPP via DECnet is discussed. This integrated approach to programming the MPP is a valuable tool for the implementation of interactive user driver systems that require the computational capabilities of the MPP as well as a controlled user view. It is expected that this methodology will be used to integrate the MPP into many such systems, and thus promote greater use of the MPP by scientific researchers who are accustomed to user friendly environments

Mitochondrial protein import

Transport of nuclear-encoded precursor proteins into mitochondria includes proteolytic cleavage of aminoterminal targeting sequences in the mitochondrial matrix. We have isolated the processing activity from Neurospora crassa. The final preparation (enriched ca. 10,000-fold over cell extracts) consists of two proteins, the matrix processing peptidase (MPP, 57 kd) and a processing enhancing protein (PEP, 52 kd). The two components were isolated as monomers. PEP is about 15-fold more abundant in mitochondria than MPP. It is partly associated with the inner membrane, while MPP is soluble in the matrix. MPP alone has a low processing activity whereas PEP alone has no apparent activity. Upon recombining both, full processing activity is restored. Our data indicate that MPP contains the catalytic site and that PEP has an enhancing function. The mitochondrial processing enzyme appears to represent a new type of “signal peptidase,” different from the bacterial leader peptidase and the signal peptidase of the endoplasmic reticulum

Enhanced Higgs boson production and avoidance of CP-violation and FCNC in the MPP inspired 2HDM

The multiple point principle (MPP) can be used to suppress non--diagonal flavour transitions and CP violation in the two Higgs doublet extension of the standard model. We discuss the quasi--fixed point scenario in the MPP inspired two Higgs doublet model which leads to the enhanced production of Higgs particles at the LHC if the MPP scale is low.Comment: Talk given at the 2007 Europhysics Conference on High Energy Physics, Manchester, England, 19-25 July 2007, CERN preprint number added, references update