Lieza Danan

• Doctor of Philosophy
• Founder and CEO at LiVeritas Biosciences

Biopharmaceuticals, protein-based drugs manufactured by living cells, are some of the most powerful and effective drugs leading the fight against numerous diseases. But producing them is a notoriously difficult business. Growth conditions, purification procedures, and formulation requirements can unintentionally change the protein structure of thes...

DOI: 10.1002/elps.201900325 The cover picture shows direct coupling of an imaged capillary isoelectric focusing (iCIEF) microchip to a high‐resolution MS detector for characterization of intact biotherapeutic protein charge variants. Real‐time monitoring of the focusing and chemical mobilization phases of the assay is performed using absorbance ima...

A microfluidic system has been designed that integrates both imaged capillary isoelectric focusing (iCIEF) separations and downstream MS detection into a single assay. Along with the construction of novel instrumentation and an innovative microfluidic chip, conversion to MS‐compatible separation reagents has also been established. Incorporation of...

concentrates intact protein isoforms into highly resolved bands but coupling of cIEF to high-resolution MS has been a longstanding challenge. Here, we utilize a microchip iCIEF device with electrokinetic migration of protein isoforms toward an ElectroSpray Ionization (ESI) tip; an approach with clear advantages over previous methodologies. We succe...

Charge heterogeneity analysis is essential for the successful development and production of therapeutic proteins. cIEF is a proven, powerful approach for analyzing these charge isoforms as many protein modifications and degradation products affect isoelectric point. MS with the capability of separating mass isoforms and charge neutral protein alter...

Analysis of serum protein glycovariants has the potential to identify new biomarkers of human disease. However, the inability to rapidly quantify glycans in a site-specific fashion remains the major barrier to applying such biomarkers clinically. Advancements in sample preparation and glycopeptide quantification are thus needed to better bridge gly...

The 2017 11th Workshop on Recent Issues in Bioanalysis (11th WRIB) took place in Los Angeles/Universal City, California on 3-7 April 2017 with participation of close to 750 professionals from pharmaceutical/biopharmaceutical companies, biotechnology companies, contract research organizations and regulatory agencies worldwide. WRIB was once again a...

Amide-linked homopolymers of sialic acid offer the advantages of stable secondary structure and increased bioavailability making them useful constructs for pharmaceutical design and drug delivery. Defining the structural characteristics that give rise to secondary structure in aqueous solution is challenging in homopolymeric material due to spectra...

The analysis of heparan sulfate glycosaminoglycans (HSGAGs) variations in human serum at the disaccharide level has a great potential for disease diagnosis and prognosis. However, the lack of available analytical methodology for the compositional analysis of HSGAGs in human serum remains to be addressed to delineate the possible role of HSGAGs on t...

A fully synthetic trivalent mimotope of gp120 conjugated to pan allelic HLA DR binding epitope was prepared using solid-phase peptide synthesis and optimized copper-catalyzed azide-alkyne cycloaddition. The methodology efficiently provides chemically uniform heteromultimeric peptide constructs with enhanced binding, avidity, and specificity toward...

Human tyrosylprotein sulfotransferases catalyze the transfer of a sulfuryl moiety from the universal sulfate donor PAPS to the hydroxyl substituent of tyrosine residues in proteins and peptides to yield tyrosine sulfated products and PAP. Tyrosine sulfation occurs in the trans-Golgi network, affecting an estimated 1% of the tyrosine residues in all...

Protein tyrosine O-sulfation, a widespread post-translational modification, is mediated by two Golgi enzymes, tyrosylprotein sulfotransferase-1 and -2. These enzymes catalyze the transfer of sulfate from the universal sulfate donor 3'-phosphoadenosine-5'-phosphosulfate (PAPS) to the hydroxyl group of tyrosine residues to form tyrosine O-sulfate est...

We measured lead and mercury in samples collected from 31 homes in communities near the former Clark Air Base, Philippines during May and October 2002. Sample media included water used for drinking and cooking, house dust and entryway soil. Composite samples of 15 food items purchased at local markets were also collected. Samples were analyzed for...