Potencial da PEGuilação para o desenvolvimento de proteínas para fins terapêuticos e analíticos

Protein PEGylation is the covalent bonding of polyethylene glycol (PEG) polymers to amino acid residues of the protein and it is one of the most promising techniques for improving the therapeutic effect of biopharmaceuticals and long-term stability of protein-based biosensors. This chemical modification brings advantages to biopharmaceuticals, such as an increased half-life, enhanced stability, and reduced immunogenicity. Moreover, in the analytical field, PEGylation improves the multiple properties of protein-based biosensors including biocompatibility, thermal and long-term stability, and solubility in organic solvents. However, the use of PEGylated conjugates in the analytical and therapeutic fields has not been widely explored. The limited industrial application of PEGylated bioconjugates can be attributed to the fact that the reaction and separation steps are currently a challenge. The correct selection of the PEGylation reaction design and the purification process are important challenges in the field of bioconjugation. In this sense, the design and optimization of site-specific PEGylation reactions and application of aqueous biphasic systems (ABS) as purification platforms for PEGylated conjugates are the two main objectives of this thesis. Regarding the purification step, the efficient fractionation (i) of the PEGylated conjugates from the native protein and (ii) of the PEGylated conjugates based on their degree of PEGylation was studied. Centrifugal partition chromatography (CPC) was applied as a continuous regime platform based on ABS technology to efficiently purify the PEGylated proteins. The two proteins under study are L-asparaginase, an important biopharmaceutical applied in the treatment of acute lymphoblastic leukemia and cytochrome c, a promising biosensor. The current work developed in this thesis demonstrates the great potential of ABS in the fractionation of PEGylated proteins, under batch and continuous regime. In addition, in situ recovery of the PEGylated products through one-pot bioconjugation and ABS purification was successfully demonstrated for both enzymes studied. Although further research on scale-up is still required, the results presented show the relevance of ABS platforms for the development of separation processes of PEGylated proteins.A PEGuilação de proteínas é a ligação covalente de polímeros de polietilenoglicol (PEG) a resíduos de aminoácidos da proteína e é uma das técnicas mais promissoras para melhorar o efeito terapêutico dos biofármacos e a estabilidade a longo prazo de biossensores proteícos. Esta modificação química traz vantagens aos produtos biofarmacêuticos, como um aumento da meia-vida, maior estabilidade e imunogenicidade reduzida. Além disso, no campo analítico, a PEGuilação melhora as múltiplas propriedades dos biossensores baseados em proteínas, incluindo biocompatibilidade, estabilidade térmica e a longo prazo, e solubilidade em solventes orgânicos. No entanto, o uso de conjugados PEGuilados em campos analíticos e terapêuticos não tem sido amplamente explorado. A aplicação industrial limitada dos bioconjugados PEGuilados pode ser atribuída ao facto de as etapas de reacção e separação serem atualmente um desafio. A seleção correcta do design da reacção de PEGuilação e do processo de purificação são importantes desafios no campo da bioconjugação. Neste sentido, a concepção e otimização de reações de PEGuilação sítio-específicas e aplicação de sistemas aquosos bifásicos (ABS) como plataformas de purificação de conjugados PEGuilados são os dois principais objetivos desta tese. No que concerne à etapa de purificação foi estudado o eficiente fracionamento (i) dos conjugados PEGuilados, da proteína nativa e (ii) dos conjugados PEGuilados baseados no seu grau de PEGuilação. A cromatografia por partição centrífuga (CPC) foi aplicada como uma plataforma de regime contínuo baseada na tecnologia de ABS para purificar eficientemente as proteínas PEGuiladas. As duas proteínas em estudo são a L-asparaginase, importante biofármaco aplicado no tratamento da leucemia linfoblástica aguda e o citocromo c, um potencial biossensor. A partir dos trabalhos desenvolvidos, é possível confirmar o grande potencial dos ABS no fracionamento de proteínas PEGuiladas, em regime contínuo e descontínuo. Além disso, a recuperação in situ dos produtos PEGuilados através da integração em uma única etapa de bioconjugação e purificação por ABS foi comprovada com sucesso para ambas as enzimas estudadas. Embora ainda sejam necessários estudos adicionais sobre a viabilidade destes sistemas em larga escala, os resultados aqui apresentados demonstram a relevância dos ABS para o desenvolvimento de processos de separação de proteínas PEGuiladas.Programa Doutoral em Engenharia Químic

Estudo de novos processos downstream com base em métodos de FPLC e SAB

Mestrado em Biotecnologia - Biotecnologia Industrial e AmbientalThe main objective of this work was the design of novel downstream processes for analytical and biotechnological applications. This work was divided in three major topics: formulation of novel polymer-based ABS systems with innovative use of IL as electrolytes; design of aqueous biphasic systems as an alternative for extraction of benzoylecgnonine and two hallucinogens (harmine and harmaline); FPLC purification of L-Asparaginase I. For each chapter, a detailed summary is presented. The downstream processes herein studied namely ABS and FPLC are good alternatives, due to the high yields and enhanced selectivity obtained. Moreover, they are relatively simple and fast from the operational point of view, present a low cost and are easy to scale up. The analytical studies show that further work is required for the application of ABS as drug extracting platforms, mainly because of the very low concentration of drugs in complex matrixes, such as urine and Ayahuasca. Better results were obtained using ABS as biotechnological extracting platforms, being possible to maximize the extractive performance of Cyt c and CA, using low concentrations of IL (0.1 wt%) as electrolytes. Furthermore, the FPLC purification of His-Tagg recombinant ASPase I was successfully performed, obtaining a recovery of 81.03 ± 0.01 % and a purification factor of 17 times relatively to the original sample from fermentation broth.O objetivo principal deste trabalho foi a concepção de novos processos downstream para aplicações analíticas e biotecnológicas. Este trabalho foi dividido em três partes principais: formulação de novos SAB formados por polímeros, dependentes do uso inovador de líquidos iónicos como eletrólitos; design de sistemas aquosos bifásicos como uma alternativa para a extração da benzoilecgnonina e dois alucinógenos (harmina e harmalina); purificação por FPLC da L – Asparaginase I. Para cada capítulo, um resumo mais detalhado foi elaborado. Mostra-se que os bioprocessos de separação aqui estudados nomeadamente SAB e FPLC são alternativas viáveis às demais, devido aos altos rendimentos e maior seletividade obtidos. Para além disso, estes são relativamente simples e rápidos e de um ponto de vista operacional, apresentam baixo custo e são fáceis de escalonar. A partir dos estudos analíticos, concluiu-se que mais trabalhos são necessários para a aplicação de SABs como plataformas de extracção de drogas ilícitas, principalmente por causa da baixa concentração das mesmas em matrizes complexas, como a urina e Ayahuasca. Melhores resultados foram obtidos, quando se utilizou os SABs como plataformas de extracção de compostos biotecnológicos, em que foi possível maximizar o desempenho de extracção tanto do citocromo c como do ácido cloranílico, utilizando baixas concentrações de líquido iónico (0,1 % em massa), como eletrólitos. Também a purificação por FPLC da His-Tagg ASPase I recombinante foi efectuada com sucesso, obtendo uma recuperação de 81,03 ± 0,01 % e um fator de purificação 17 vezes relativamente à amostra original, proveniente do meio fermentativo

Protein PEGylation for the design of biobetters: from reaction to purification processes

The covalent attachment of polyethylene glycol (PEG) to therapeutical proteins is an important route to develop biobetters for biomedical, biotech and pharmaceutical industries. PEG conjugation can shield antigenic epitopes of the protein, reduce degradation by proteolytic enzymes, enhance long-term stability and maintain or even improve pharmacokinetic and pharmacodynamics characteristics of the protein drug. Nonetheless, correct information in terms of the PEGylation process from reaction to downstream processing is of paramount importance for the industrial application and processing scale-up. In this review we present and discuss the main steps in protein PEGylation, namely: PEGylation reaction, separation of the products and final characterization of structure and activity of the resulting species. These steps are not trivial tasks, reason why bioprocessing operations based on PEGylated proteins relies on the use of analytical tools according to the specific pharmaceutical conjugate that is being developed. Therefore, the appropriate selection of the technical and analytical methods may ensure success in implementing a feasible industrial process

Development of L-Asparaginase Biobetters: Current Research Status and Review of the Desirable Quality Profiles

L-Asparaginase (ASNase) is a vital component of the first line treatment of acute lymphoblastic leukemia (ALL), an aggressive type of blood cancer expected to afflict over 53,000 people worldwide by 2020. More recently, ASNase has also been shown to have potential for preventing metastasis from solid tumors. The ASNase treatment is, however, characterized by a plethora of potential side effects, ranging from immune reactions to severe toxicity. Consequently, in accordance with Quality-by-Design (QbD) principles, ingenious new products tailored to minimize adverse reactions while increasing patient survival have been devised. In the following pages, the reader is invited for a brief discussion on the most recent developments in this field. Firstly, the review presents an outline of the recent improvements on the manufacturing and formulation processes, which can severely influence important aspects of the product quality profile, such as contamination, aggregation and enzymatic activity. Following, the most recent advances in protein engineering applied to the development of biobetter ASNases (i.e., with reduced glutaminase activity, proteolysis resistant and less immunogenic) using techniques such as site-directed mutagenesis, molecular dynamics, PEGylation, PASylation and bioconjugation are discussed. Afterwards, the attention is shifted toward nanomedicine including technologies such as encapsulation and immobilization, which aim at improving ASNase pharmacokinetics. Besides discussing the results of the most innovative and representative academic research, the review provides an overview of the products already available on the market or in the latest stages of development. With this, the review is intended to provide a solid background for the current product development and underpin the discussions on the target quality profile of future ASNase-based pharmaceuticals

Novel site-specific PEGylated L-asparaginase

L-asparaginase (ASNase) from Escherichia coli is currently used in some countries in its PEGylated form (ONCASPAR, pegaspargase) to treat acute lymphoblastic leukemia (ALL). PEGylation refers to the covalent attachment of poly(ethylene) glycol to the protein drug and it not only reduces the immune system activation but also decreases degradation by plasmatic proteases. However, pegaspargase is randomly PEGylated and, consequently, with a high degree of polydispersity in its final formulation. In this work we developed a site-specific N-terminus PEGylation protocol for ASNase. The monoPEG-ASNase was purified by anionic followed by size exclusion chromatography to a final purity of 99%. The highest yield of monoPEG-ASNase of 42% was obtained by the protein reaction with methoxy polyethylene glycol-carboxymethyl N-hydroxysuccinimidyl ester (10kDa) in 100 mM PBS at pH 7.5 and PEG:ASNase ratio of 25:1. The monoPEG-ASNase was found to maintain enzymatic stability for more days than ASNase, also was resistant to the plasma proteases like asparaginyl endopeptidase and cathepsin B. Additionally, monoPEG-ASNase was found to be potent against leukemic cell lines (MOLT-4 and REH) in vitro like polyPEG-ASNase. monoPEG-ASNase demonstrates its potential as a novel option for ALL treatment, being an inventive novelty that maintains the benefits of the current enzyme and solves challenges.publishe

Protein PEGylation for the design of biobetters: from reaction to purification processes

The covalent attachment of polyethylene glycol (PEG) to therapeutical proteins is an important route to develop biobetters for biomedical, biotech and pharmaceutical industries. PEG conjugation can shield antigenic epitopes of the protein, reduce degradation by proteolytic enzymes, enhance long-term stability and maintain or even improve pharmacokinetic and pharmacodynamics characteristics of the protein drug. Nonetheless, correct information in terms of the PEGylation process from reaction to downstream processing is of paramount importance for the industrial application and processing scale-up. In this review we present and discuss the main steps in protein PEGylation, namely: PEGylation reaction, separation of the products and final characterization of structure and activity of the resulting species. These steps are not trivial tasks, reason why bioprocessing operations based on PEGylated proteins relies on the use of analytical tools according to the specific pharmaceutical conjugate that is being developed. Therefore, the appropriate selection of the technical and analytical methods may ensure success in implementing a feasible industrial process

Correction: Novel site-specific PEGylated L-asparaginase.

[This corrects the article DOI: 10.1371/journal.pone.0211951.]