Low Temperature Kinetics as a Probe of Protein Structure and Dynamics

The recombination kinetics of flash-photolyzed carbon monoxy heme proteins has been studied as a function of temperature over the range of 2 K-350 K. Low temperature kinetics (< 200 K) reveal that internal activation energy barriers to recombination (a) control the room temperature kinetics, (b) are of a distributed nature, forming an ensemble of activation energies, (c) are specific to the protein studied and are sensitive to the presence of substrates bound to the protein. Cytochrome P450 from camphor induced Pseudomonas putida reveals low temperature kinetics which are highly dependent on the presence or absence of the camphor substrate

Raman spektroskopija i determinacija zemljišnih kvasaca

In this paper, two isolates of yeasts, members of the genus Candida, have been examined using Raman spectroscopy. The yeasts were isolated from soils sampled at the town park in Tivat (Montenegro) and experimental farm Radmilovac (Serbia), by the accumulation method. The pure cultures of yeasts were identified by the API 20C AUX system. The presence of Candida guilliermondii and Candida utilis was noted. The Raman spectra, originating from lipids, amides, proteins, carbohydrates, aromatic amino acids and the nucleotide bases, were analyzed in the wide range of the wave numbers from 500 to 3200 cm-1. It was noticed that peaks which correspond to the lipid fraction were more pronounced in the case of Candida guilliermondii compared to Candida utilis. This may represent a specific response of the yeast species to stress conditions.U ovom radu su Raman spektroskopijom ispitivana dva izolata kvasaca iz roda Candida. Izolacija kvasaca je izvršena iz zemljišta uzetog iz gradskog parka u Tivtu (Crna Gora) i sa oglednog dobra Radmilovac (Poljoprivredni fakultet, Beograd, Srbija), metodom nakupljanja. Dobijene čiste kulture kvasaca identifikovane su primenom API AUX 20C sistema (bioMerieux-Vitek). Konstatovano je prisustvo vrsta Candida guilliermondii i Candida utilis. Analizirani su Raman spektri koji potiču od lipida, amida, proteina, ugljenih hidrata, aromatičnih aminokiselina i nukleotidnih baza, u širokoj oblasti talasnih brojeva, od 500 do 3200 cm-1. Utvrđeno je da su kod kvasca Candida guilliermondii pikovi koji odgovaraju frakciji lipida bitno izraženiji nego kod Candida utilis, što može predstavljati specifičan odgovor date vrste kvasca na stres

Iron transfer and storage proteins

Željezo je vrlo bitan element za temeljne metaboličke procese. S obzirom na činjenicu da je neophodan za niz funkcija, organizmi ga moraju pohranjivati na način da bude netoksičan i brzo dostupan. To je postignuto „pakiranjem“ željeza u proteinske omotače zvane feritini. Feritini su simetrični proteini koji se sastoje od jezgre izgrađene od kompleksa željezovog oksida i hidroksida te proteinske ljuske. Željezo se iz mononuklearno-fagocitnog sustava (,,reciklaža'' eritrocita) i tankog crijeva (ulazak preko probavnog sustava) do svih stanica prenosi transferinom. On ima izrazito veliki afinitet za slobodno željezo, a u stanicu ulazi endocitozom induciranom receptorom gdje ga ispušta u uvjetima nižeg pH. Mehanizam unutarstanične regulacije željeza precizno je reguliran na razini translacije. Citosolna akonitaza u uvjetima smanjene koncentracije željeza gubi svoj Fe-S klaster i kao takva se može vezati na mRNA feritina i transferinskog receptora. U tom se slučaju sinteza feritina smanjuje (pohrana nije toliko bitna), dok se sinteza transferinskog receptora povećava. Porastom broja receptora na površini stanice u nju ulazi više željeza pa tako stanice koje imaju veće potrebe za tim elementom imati izražen veći broj receptora. Željezo se još može nalaziti u obliku hemosiderina, proteina koji je često pokazatelj viška željeza u organizmu. Ostali bitni proteini koji sadrže željezo su hemoproteini i proteini s klasterima željeza i sumpora. Željezo u hemu najčešće ima funkciju reverzibilnog vezanja kisika i transporta elektrona. U hemoglobinu se nalazi preko 60% ukupnog željeza u organizmu. Hemoproteini, kao i Fe-S proteini, bitnu ulogu ostvaruju i u staničnom disanju kao prijenosnici elektrona. Dakle, željezo je element s mnoštvom različitih funkcija te je stoga neophodan za život svih organizama na Zemlji.Iron is an important element for fundamental metabolic processes. Considering the fact that it is essential for a range of functions, it has to be stored in a non-toxic and accessible form. This is achieved by packing iron into protein shells called ferritins. Ferritins are symmetric proteins consisting of iron oxide-hydroxide core and a protein shell. Iron is tranferred from mononuclear phagocyte system (erythrocyte recycling) and duodenum (absorption by digestive system) to the entire organism by transferrin. Transferrin has extremely high affinity for free iron and is taken up by receptor-mediated endocytosis into endosomes. There it releases iron in the low pH environment. Intracellular iron regulation mechanism is precisely controlled at translation level. When the cell is depleted of iron, cytosolic aconitase loses its Fe-S cluster. Apoenzyme so formed has the ability to bind to mRNAs for transferrin receptor and ferritin, thus reducing ferritin synthesis and increasing transferrin receptor synthesis. With increase of transferrin receptor number on the cell surface, more iron is taken up by the cell. Cells with greater need for iron have more transferrin receptors on their surface. Another example of an iron storage protein is hemosiderin. It is often an indicator of excess iron in the body. Other important iron containing proteins are hemeproteins and iron-sulfur proteins. Heme iron has a function of reversible oxygen binding and electron transport. Hemoglobin contains over 60% of total body iron. Hemeproteins, together with Fe-S proteins, have an important role in cellular respiration as electron carriers. In conclusion, iron is an element with a variety of functions and is therefore essential for all living organisms on Earth

Determination of optimal temperature and pH of lactic acid bacteria isolated from acquaculture product

Bakterije mliječne kiseline se zbog svojih poželjnih karakteristika i sinteze korisnih metabolita, intenzivno koriste kao starter kulture u različitim proizvodnim procesima, a ponajprije u proizvodnji fermentirane hrane. Kako bi neki bakterijski soj postao starter kultura potrebno je provesti niz istraživanja i dokazati da je ta kultura sigurna za primjenu, tehnološki učinkovita, a njena primjena prihvatljiva s ekonomskog stajališta. Određivanje optimalnih parametara za uzgoj bakterijskih sojeva je od iznimne važnosti za njihovo buduće korištenje u proizvodnim procesima te je stoga cilj ovog rada bio odrediti optimalnu temperaturu i optimalnu pH vrijednost autohtone mikrobne populacije bakterija mliječne kiseline izoliranih iz riba i školjkaša Jadranskog mora. Utvrđeno je da je za rast sojeva Lactobacillus plantarum D1 i Lactobacillus plantarum K4 optimalna temperatura 28°C a za Lactobacillus plantarum O1, Lactobacillus helveticus O9 i Leuconostoc mesenteroides L4A 37°C. Optimalna pH vrijednost za L. plantarum D1, L. plantarum K4, L. helveticus O9 i L. mesenteroides iznosi 6.0, dok L. plantarum O1 najbolje preživljavljava pri pH 4.0.The lactic acid bacteria, due to their desirable characteristics and synthesis of useful metabolites, are intensely used as starter cultures in different production processes, and above all in fermented food production. In order for some bacterial strain to become a starter culture, it is necessary to conduct a series of researches and prove that this culture is safe for use, technologically efficient and its application is acceptable from an economic point of view. Determination of optimal parameters for cultivation of bacterial strains is very important for their future use in production processes and therefore the purpose of this paper was determine the optimal temperature and optimum pH value of the autochtonus microbal population of lactic acid bacteria isolated from fish and shelfish. It was found that optimal temperature for growth of Lactobacillus plantarum D1 and Lactobacillus plantarum K4 is 28 °C and for Lactobacillus plantarum O1, Lactobacillus helveticus O9 and Leuconostoc mesenteroides L4A is 37 °C. The optimal pH value for Lactobacillus plantarum D1, Lactobacillus plantarum K4, Lactobacillus helveticus O9 and Leuconostoc mesenteroides is 6.0, while L. plantarum O1 survives at pH 4.0

IMPLICANCIAS CLÍNICAS DE LA REGULACIÓN DEL TONO VASCULAR

La regulación del tono vascular es considerada como una de las funciones del endotelio que ha cobrado gran importancia en las últimas décadas, la comprensión de antiguos conocimientos y el descubrimiento de nuevos mecanismos biomoleculares y bioquímicos que determinan el equilibrio entre la vasodilatación y vasoconstricción así como el mantenimiento de la tonicidad del endotelio permitirá el descubrimiento de nuevas moléculas para el tratamiento de múltiples enfermedades tanto agudas como crónicas. En esta revisión se pretende actualizar básicamente la función de los factores dependientes de endotelio que median el vaso dilatación y vasoconstricción del músculo liso vascular y su implicancia clínica resaltando los más importantes por lo amplio del tema