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  <xsd:element id="akao_LongtermDebtMaturitiesPaymentofFinalFee" name="LongtermDebtMaturitiesPaymentofFinalFee" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="akao_LongtermDebtMaturitiesRepaymentsofPrincipalTotal" name="LongtermDebtMaturitiesRepaymentsofPrincipalTotal" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="akao_LongtermDebtMaturitiesRepaymentsofPrincipalandFinalFeeTotal" name="LongtermDebtMaturitiesRepaymentsofPrincipalandFinalFeeTotal" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="akao_MilestonePaymentAmount" name="MilestonePaymentAmount" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="instant" />
  <xsd:element id="akao_MilestonePaymentsForFirstCommercialProduct" name="MilestonePaymentsForFirstCommercialProduct" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="akao_MilestonePaymentsForSecondCommercialProduct" name="MilestonePaymentsForSecondCommercialProduct" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_MonteCarloSimulationMember" name="MonteCarloSimulationMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_NationalInstituteOfAllergyAndInfectiousDiseasesMember" name="NationalInstituteOfAllergyAndInfectiousDiseasesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_November12011WarrantsMember" name="November12011WarrantsMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_OnemonthLIBORMember" name="OnemonthLIBORMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="akao_OperatingLeasesSquareFootage" name="OperatingLeasesSquareFootage" nillable="true" substitutionGroup="xbrli:item" type="num:areaItemType" xbrli:periodType="instant" />
  <xsd:element id="akao_OperatingLeasesSubleaseSquareFootage" name="OperatingLeasesSubleaseSquareFootage" nillable="true" substitutionGroup="xbrli:item" type="num:areaItemType" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="akao_OxfordFinanceCorporationAndSiliconValleyBankLoanPayableMember" name="OxfordFinanceCorporationAndSiliconValleyBankLoanPayableMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_OxfordFinanceLLCMember" name="OxfordFinanceLLCMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_PharmaceuticalOrganizationMember" name="PharmaceuticalOrganizationMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="akao_ProceedfromIssuanceofCommonStockGrossofIssuanceCosts" name="ProceedfromIssuanceofCommonStockGrossofIssuanceCosts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="akao_ProceedsfromIssuanceofCommonStockNetofCommissionsandOtherCosts" name="ProceedsfromIssuanceofCommonStockNetofCommissionsandOtherCosts" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="akao_ResearchAndDevelopmentGrantAndOtherRevenues" name="ResearchAndDevelopmentGrantAndOtherRevenues" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="akao_ResearchandDevelopmentGrantAdditionalContractFunding" name="ResearchandDevelopmentGrantAdditionalContractFunding" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element id="akao_ResearchandDevelopmentRemainingAvailableFunding" name="ResearchandDevelopmentRemainingAvailableFunding" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="instant" />
  <xsd:element abstract="true" id="akao_RestrictedCashMember" name="RestrictedCashMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="akao_RevaluationofDerivativeLiability" name="RevaluationofDerivativeLiability" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="debit" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_SeriesAConvertiblePreferredStockMember" name="SeriesAConvertiblePreferredStockMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="akao_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantExercisedInPeriod" name="ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrantExercisedInPeriod" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsSharesAvailableForGrantRollForward" name="SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsSharesAvailableForGrantRollForward" nillable="true" substitutionGroup="xbrli:item" type="xbrli:stringItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_SiliconValleyBankMember" name="SiliconValleyBankMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_SouthSanFranciscoMember" name="SouthSanFranciscoMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_StockIncentivePlanTwoThousandFourteenMember" name="StockIncentivePlanTwoThousandFourteenMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_StockIncentivePlanTwoThousandThreeMember" name="StockIncentivePlanTwoThousandThreeMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element id="akao_StockIssuedDuringPeriodSharesToUnderwritersForExerciseOfOverAllotmentOption" name="StockIssuedDuringPeriodSharesToUnderwritersForExerciseOfOverAllotmentOption" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="akao_StockOptionGrantedVestingUponAchievementOfStockPriceTarget" name="StockOptionGrantedVestingUponAchievementOfStockPriceTarget" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="akao_TemporaryEquityNumberofTranches" name="TemporaryEquityNumberofTranches" nillable="true" substitutionGroup="xbrli:item" type="xbrli:integerItemType" xbrli:periodType="duration" />
  <xsd:element id="akao_TemporaryEquityStockIssuedDuringPeriodSharesNewIssues" name="TemporaryEquityStockIssuedDuringPeriodSharesNewIssues" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="akao_TemporaryEquityStockIssuedDuringPeriodSharesRelatedPartyConvertibleLoanPayable" name="TemporaryEquityStockIssuedDuringPeriodSharesRelatedPartyConvertibleLoanPayable" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="akao_TemporaryEquityStockIssuedDuringPeriodSharesRelatedPartyConvertibleNotesPayable" name="TemporaryEquityStockIssuedDuringPeriodSharesRelatedPartyConvertibleNotesPayable" nillable="true" substitutionGroup="xbrli:item" type="xbrli:sharesItemType" xbrli:periodType="duration" />
  <xsd:element id="akao_TemporaryEquityStockIssuedDuringPeriodValueRelatedPartyConvertibleLoanPayable" name="TemporaryEquityStockIssuedDuringPeriodValueRelatedPartyConvertibleLoanPayable" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="akao_TemporaryEquityStockIssuedDuringPeriodValueRelatedPartyConvertibleNotesPayable" name="TemporaryEquityStockIssuedDuringPeriodValueRelatedPartyConvertibleNotesPayable" nillable="true" substitutionGroup="xbrli:item" type="xbrli:monetaryItemType" xbrli:balance="credit" xbrli:periodType="duration" />
  <xsd:element id="akao_TermOfAgreement" name="TermOfAgreement" nillable="true" substitutionGroup="xbrli:item" type="xbrli:durationItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_ThreemonthLIBORMember" name="ThreemonthLIBORMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_TwoThousandFourteenEmploymentCommencementIncentivePlanMember" name="TwoThousandFourteenEmploymentCommencementIncentivePlanMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_TwoThousandTenWellcomeFundingAgreementMember" name="TwoThousandTenWellcomeFundingAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_TwoThousandTwelveBridgeLoanAgreementMember" name="TwoThousandTwelveBridgeLoanAgreementMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_UpfrontLicenseFeesMember" name="UpfrontLicenseFeesMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_WarrantToPurchaseCommonStockMember" name="WarrantToPurchaseCommonStockMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_WarrantsToPurchaseConvertiblePreferredStockMember" name="WarrantsToPurchaseConvertiblePreferredStockMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
  <xsd:element abstract="true" id="akao_WarrantsToPurchaseSeriescConvertiblePreferredStockMember" name="WarrantsToPurchaseSeriescConvertiblePreferredStockMember" nillable="true" substitutionGroup="xbrli:item" type="nonnum:domainItemType" xbrli:periodType="duration" />
</xsd:schema>


